@article{tsen_kiang_ferry_kochelap_komirenko_kim_morkoc_2006, title={Subpicosecond Raman studies of electric-field-induced optical phonon instability in an In0.53Ga0.47As-based semiconductor nanostructure}, volume={18}, ISSN={0953-8984 1361-648X}, url={http://dx.doi.org/10.1088/0953-8984/18/34/009}, DOI={10.1088/0953-8984/18/34/009}, abstractNote={Transient carrier transport phenomena in an In0.53Ga0.47As-based p–i–n semiconductor nanostructure have been studied by using subpicosecond transient/time-resolved Raman spectroscopy. We observe an instability of the GaAs-like optical phonon population in this nanostructure semiconductor that occurs when electrons are accelerated to very high velocities by the application of intense electric fields. The results open up a new channel for creating coherent THz frequency that can be used in THz electronic devices. We suggest that the observed phenomena will have enormous impact on the carrier dynamics and carrier transport in nanoscale semiconductor electronic devices.}, number={34}, journal={Journal of Physics: Condensed Matter}, publisher={IOP Publishing}, author={Tsen, K T and Kiang, Juliann G and Ferry, D K and Kochelap, V A and Komirenko, S M and Kim, K W and Morkoc, H}, year={2006}, month={Aug}, pages={7961–7974} }
 @article{komirenko_kim_kochelap_woolard_2004, title={Low-field electron runaway and spontaneous formation of two-beam velocity distribution in polar semiconductors}, volume={69}, ISSN={1098-0121 1550-235X}, url={http://dx.doi.org/10.1103/PhysRevB.69.233201}, DOI={10.1103/physrevb.69.233201}, abstractNote={We show that high-energy electron injection into a polar semiconductor can lead to a spontaneous splitting of the electron beam into two distinct groups with different velocity distributions. While one group of electrons experiences thermalization in a given subthreshold field, the velocity and energy of the second group increases with distance due to the previously unknown low-field electron runaway effect. We investigate the dependence of the carrier distribution on the injection energy, and show that the overall distribution exhibits a partial population inversion with a distance-dependent energy gap between the thermalized and runaway electrons. The low-field runaway is a universal effect which is characteristic of nanoscale semiconductors where polar optical phonon scattering predominates and there is a large intervalley energy separation as in the group-III nitride heterostructures.}, number={23}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Komirenko, S. M. and Kim, K. W. and Kochelap, V. A. and Woolard, D. L.}, year={2004}, month={Jun} }
 @article{zavada_komirenko_kim_kochelap_2003, title={Efficient nitride-based short-wavelength emitters with enhanced hole injection}, volume={174}, number={2003}, journal={Compound Semiconductors 2002}, author={Zavada, J. M. and Komirenko, S. M. and Kim, K. W. and Kochelap, V. A.}, year={2003}, pages={401–404} }
 @article{komirenko_kim_kochelap_zavada_2003, title={Enhancement of hole injection for nitride-based light-emitting devices}, volume={47}, ISSN={0038-1101}, url={http://dx.doi.org/10.1016/S0038-1101(02)00314-3}, DOI={10.1016/S0038-1101(02)00314-3}, abstractNote={A novel device design is proposed for a strong enhancement of hole injection current in nitride-based light-emitting heterostructures. Preliminary calculations show orders of magnitude increase in injected hole current when using the proposed superlattice hole injector device based on the real-space transfer concept.}, number={1}, journal={Solid-State Electronics}, publisher={Elsevier BV}, author={Komirenko, S.M and Kim, K.W and Kochelap, V.A and Zavada, J.M}, year={2003}, month={Jan}, pages={169–171} }
 @article{komirenko_kim_kochelap_koroteev_stroscio_2003, title={Nonlinear regimes of coherent optical phonon generation in quantum wells under electric current pumping}, volume={68}, ISSN={0163-1829 1095-3795}, url={http://dx.doi.org/10.1103/PhysRevB.68.155308}, DOI={10.1103/physrevb.68.155308}, abstractNote={We present an analysis of nonlinear regimes of the coherent optical phonon generation under the electron drift in quantum wells. The phonon and electron subsystems are treated self-consistently. This allows us to find thesteady-state generation regimes with macroscopic populations of optical phonon modes and the electron transport controlled in part by the generated phonons. The generation regimes demonstrate a pronounced threshold character. At high electric fields above the threshold, practically single-mode generation occurs and the current-voltage characteristic is considerably changed. We demonstrate high efficiency generation of the coherent optical phonons by the electric current. The coherent macroscopic optical displacements and the amplitudes of oscillating electrostatic fields are evaluated. The proposed model based on the electron nonlinearities predicts a range of the pumping electric fields under which the steady state phonon generation is realized. Our results suggest that the phonon avalanche occurs beyond this field range.}, number={15}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Komirenko, S. M. and Kim, K. W. and Kochelap, V. A. and Koroteev, V. V. and Stroscio, M. A.}, year={2003}, month={Oct} }
 @article{liang_tsen_sankey_komirenko_kim_kochelap_wu_ho_ho_morkoç_2003, title={Observation of optical phonon instability induced by drifting electrons in semiconductor nanostructures}, volume={82}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.1563730}, DOI={10.1063/1.1563730}, abstractNote={We have experimentally proven the Cerenkov generation of optical phonons by drifting electrons in a semiconductor. We observe an instability of the polar optical phonons in nanoscale semiconductors that occurs when electrons are accelerated to very high velocities by intense electric fields. The instability is observed when the electron drift velocity is larger than the phase velocity of optical phonons and rather resembles a “sonic boom” for optical phonons. The effect is demonstrated in p–i–n semiconductor nanostructures by using subpicosecond Raman spectroscopy.}, number={12}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Liang, W. and Tsen, K. T. and Sankey, Otto F. and Komirenko, S. M. and Kim, K. W. and Kochelap, V. A. and Wu, Meng-Chyi and Ho, Chong-Long and Ho, Wen-Jeng and Morkoç, H.}, year={2003}, month={Mar}, pages={1968–1970} }
 @article{komirenko_kim_kochelap_stroscio_2002, title={Confinement and amplification of acoustic waves in cubic heterostructures}, volume={65}, ISSN={0163-1829 1095-3795}, url={http://dx.doi.org/10.1103/PhysRevB.65.155321}, DOI={10.1103/physrevb.65.155321}, abstractNote={We present the theory of acoustic phonon confinement in elastically anisotropic (cubic) quantum-well (QW) heterostructures grown in a direction of high symmetry. A general criterion for phonon confinement is derived. For Si/Si 0 . 5 Ge 0 . 5 /Si, Si/Ge/Si and AlAs/GaAs/AlAs QW heterostructures, dispersion curves are obtained, and displacement fields corresponding to the confined phonons are studied in detail. It is found that the confinement of acoustic phonons in these QW layers is strong in the subterahertz and terahertz frequency ranges. The resulting description of phonon confinement is applied to analyze the amplification of confined modes by the drift of the two-dimensional carriers as a function of the phonon frequency, the temperature, and the parameters of heterostructure. The calculation shows that the amplification coefficient of the confined phonons can exceed 10 3 cm - 1 for Si/Ge-based structures and 10 2 cm - 1 for AlAs/GaAs-based structures.}, number={15}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Komirenko, S. M. and Kim, K. W. and Kochelap, V. A. and Stroscio, M. A.}, year={2002}, month={Apr} }
 @article{komirenko_kim_kochelap_stroscio_2002, title={Confinement and amplification of terahertz acoustic phonons in cubic heterostructures}, volume={316-317}, ISSN={0921-4526}, url={http://dx.doi.org/10.1016/S0921-4526(02)00506-9}, DOI={10.1016/S0921-4526(02)00506-9}, abstractNote={A general criterion for phonon confinement is derived in the model of elastically anisotropic (cubic) media. The results are applied to the calculation of the dispersion curves of the confined phonons in Si/Si1−xGex/Si and AlAs/GaAs/AlAs heterostructures. For these structures, we show that the lowest-order phonon branches behave differently from those in the model of isotropic media. We have found that confinement is strong in the terahertz frequency range. For p-Si/SiGe/Si and n-AlAs/GaAs/AlAs quantum well heterostructures, we have studied the effect of amplification of confined high-frequency phonons by the drift of low-dimensional carriers. Two electron–phonon interaction mechanisms were taken into account: interaction via the deformation potential (p-SiGe and n-AlGaAs) and the piezoelectric interaction (n-AlGaAs). It was found that an amplification coefficient of the order of 102cm−1 for the AlGaAs heterostructures and 103cm−1 for the SiGe heterostructures can be obtained in spectrally-separated narrow amplification bands.}, journal={Physica B: Condensed Matter}, publisher={Elsevier BV}, author={Komirenko, S.M. and Kim, K.W. and Kochelap, V.A. and Stroscio, M.A.}, year={2002}, month={May}, pages={356–358} }
 @article{komirenko_kim_kochelap_zavada_2002, title={Laterally doped heterostructures for III–N lasing devices}, volume={81}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.1527985}, DOI={10.1063/1.1527985}, abstractNote={To achieve a high-density electron-hole plasma in group-III nitrides for efficient light emission, we propose a planar two-dimensional (2D) p-i-n structure that can be formed in the quantum well layers due to efficient activation of donors and acceptors in the laterally, selectively doped barriers. We show that strongly nonequilibrium 2D electron-hole plasma with density above 1012 cm−2 can be realized in the i region of the laterally biased p-i-n structure, enabling the formation of interband population inversion and stimulated emission from such a lateral current pumped emitter (LACE). We suggest that implementation of the lateral p-i-n structures provides an efficient way of utilizing potential-profile-enhanced doping of superlattices and quantum wells for electric pumping of nitride-based lasers.}, number={24}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Komirenko, S. M. and Kim, K. W. and Kochelap, V. A. and Zavada, J. M.}, year={2002}, month={Dec}, pages={4616–4618} }
 @article{stroscio_dutta_kahn_kim_komirenko_2002, title={Phonons in nanostructures: device applications}, volume={316-317}, ISSN={0921-4526}, url={http://dx.doi.org/10.1016/S0921-4526(02)00418-0}, DOI={10.1016/s0921-4526(02)00418-0}, abstractNote={This review highlights the utility of the dielectric and elastic continuum models for describing phonons in nanostructures. The properties of confined, interface and propagating modes in wurtzite quantum-confined structures may be described theoretically in terms of the dielectric continuum and Loudon's model for uniaxial semiconductors. Moreover, dimensionally confined acoustic phonon modes in nanostructures and carbon nanotubes may be described in terms of the elastic continuum models.}, journal={Physica B: Condensed Matter}, publisher={Elsevier BV}, author={Stroscio, M. and Dutta, M. and Kahn, D. and Kim, K.W. and Komirenko, S.}, year={2002}, month={May}, pages={8–11} }
 @article{komirenko_kim_demidenko_kochelap_stroscio_2001, title={Amplification of transverse acoustic phonons in quantum well heterostructures with piezoelectric interaction}, volume={90}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.1402145}, DOI={10.1063/1.1402145}, abstractNote={We have analyzed amplification of transverse phonons confined in quantum well (QW) heterostructures through piezoelectric electron–phonon interaction with drifting electrons. It was found that this mechanism of interaction couples the low-dimensional electrons and the shear-horizontal (SH) confined phonons. We have studied the electrostatic potential accompanying the SH waves and found that efficient interaction can be achieved for the lowest antisymmetric SH phonon branch in a narrow band of phonon frequencies. For AlGaAs QWs the amplification coefficient was calculated to be on the order of 100 cm−1 in the sub-THz phonon frequency range. These results suggest an electrical method for coherent phonon generation in the technologically well-developed AlGaAs QW heterostructures.}, number={8}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Komirenko, S. M. and Kim, K. W. and Demidenko, A. A. and Kochelap, V. A. and Stroscio, M. A.}, year={2001}, month={Oct}, pages={3934–3941} }
 @article{komirenko_kim_stroscio_dutta_2001, title={Applicability of the Fermi golden rule and the possibility of low-field runaway transport in nitrides}, volume={13}, ISSN={0953-8984 1361-648X}, url={http://dx.doi.org/10.1088/0953-8984/13/28/306}, DOI={10.1088/0953-8984/13/28/306}, abstractNote={We investigated electron transport characteristics of wide-band polar semi-conductors with intermediate strength of the electron–phonon interaction. Electron energy loss to the lattice was calculated as a function of electron velocity for various materials in the frameworks of (a) a perturbative approach based on the calculation of scattering rates from Fermi's golden rule and (b) a non-perturbative approach based on the path-integral formalism of Thornber and Feynman. Our results suggest that the standard perturbative treatment can be applied to GaN and AlN despite the relatively strong electron–phonon coupling in this material system, with intercollision times of the order of the period of the phonon oscillation. Our findings also indicate the possibility for unique long-distance runaway transport in nitrides which may occur at the pre-threshold electric fields. The polaron ground-state energy and effective masses are calculated for GaN and AlN as well as for GaAs and Al2O3. An expression for the Fröhlich coupling constant for wurtzites is derived.}, number={28}, journal={Journal of Physics: Condensed Matter}, publisher={IOP Publishing}, author={Komirenko, S M and Kim, K W and Stroscio, M A and Dutta, M}, year={2001}, month={Jun}, pages={6233–6246} }
 @article{komirenko_kim_kochelap_fedorov_stroscio_2001, title={Generation of coherent confined LO phonons under the drift of two-dimensional electrons}, volume={63}, ISSN={0163-1829 1095-3795}, url={http://dx.doi.org/10.1103/PhysRevB.63.165308}, DOI={10.1103/physrevb.63.165308}, abstractNote={This paper addresses the effect of generation of confined LO phonons by drifting electrons in quantum wells. We have obtained a general formula for the phonon increment as a function of the phonon wave vector, the electron drift velocity, and parameters of the structure. The kinetic parameters of the drifting electrons are estimated by using momentum and energy balance equations for electron scattering by the confined optical phonons. We have performed numerical estimates of the phonon increment, as well as the phonon lifetimes, and found that AlAs/GaAs/AlAs and GaSb/InSb/GaSb quantum well structures with high drift velocities can demonstrate the effect of generation of the coherent confined optical modes. Essentially, the phonon increment has a maximum as a function of the wave vector. This implies a strong selection of the generated phonon modes. We briefly discuss the nonlinear electron mechanism which stabilizes the increase of the phonon populations and provides for the steady-state phonon generation.}, number={16}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Komirenko, S. M. and Kim, K. W. and Kochelap, V. A. and Fedorov, I. and Stroscio, M. A.}, year={2001}, month={Apr} }
 @article{komirenko_kim_kochelap_stroscio_2001, title={High-field electron transport in nanoscale group-III nitride devices}, volume={228}, ISSN={["0370-1972"]}, DOI={10.1002/1521-3951(200111)228:2<593::aid-pssb593>3.0.co;2-2}, abstractNote={Focusing on the short-size group-III nitride heterostructures, we have developed a model which takes into account main features of transport of electrons injected into a polar semiconductor under high electric fields. The model is based on an exact analytical solution of Boltzmann transport equation. The electron velocity distribution over the device is analyzed at different fields and the basic characteristics of the high-field electron transport are obtained. The critical field for the runaway regime, when electron energies and velocities increase with distance which results in the average velocities higher than the peak velocity in bulk-like samples, is determined. We have found that the runaway electrons are characterized by a distribution function with population inversion. Different nitride-based small-size devices where this effect can have an impact on the device performance are considered.}, number={2}, journal={PHYSICA STATUS SOLIDI B-BASIC RESEARCH}, author={Komirenko, SM and Kim, KW and Kochelap, VA and Stroscio, MA}, year={2001}, month={Nov}, pages={593–597} }
 @article{dutta_alexson_bergman_nemanich_dupuis_kim_komirenko_stroscio_2001, title={Phonons in III–V nitrides: Confined phonons and interface phonons}, volume={11}, ISSN={1386-9477}, url={http://dx.doi.org/10.1016/S1386-9477(01)00217-X}, DOI={10.1016/S1386-9477(01)00217-X}, abstractNote={Phonons in III–V nitrides are examined experimentally for dimensionally confined systems and for alloys of InGaN with a view towards understanding the phonon modes of these systems. Results are compared with the predictions of Loudon's model for uniaxial semiconductors. The modes of the InGaN system are compared with those of the AlGaN ternary alloy. The first Raman measurements of interface phonons in binary GaN–AlN superlattices are presented.}, number={2-3}, journal={Physica E: Low-dimensional Systems and Nanostructures}, publisher={Elsevier BV}, author={Dutta, M and Alexson, D and Bergman, L and Nemanich, R.J and Dupuis, R and Kim, K.W and Komirenko, S and Stroscio, M}, year={2001}, month={Oct}, pages={277–280} }
 @article{komirenko_kim_kochelap_stroscio_2001, title={Runaway effects in nanoscale group-III nitride semiconductor structures}, volume={64}, ISSN={0163-1829 1095-3795}, url={http://dx.doi.org/10.1103/PhysRevB.64.113207}, DOI={10.1103/physrevb.64.113207}, abstractNote={We have revisited the problem of electron runaway in strong electric fields in polar semiconductors focusing on nanoscale group-III nitride structures. By developing a transport model that accounts for the main features of electrons injected in short devices under high electric fields, we have investigated the electron distribution as a function of electron momenta and coordinates. Runaway transport is analyzed in detail. The critical field of this regime is determined for InN, GaN, and AlN. We found that the transport in the nitrides is always dissipative (i.e., no ballistic transport). For the runaway regime, however, the electrons increase their velocities with distance, which results in average velocities higher than the peak velocity in bulklike samples. We have demonstrated that the runaway electrons are characterized by a distribution function exhibiting a population inversion.}, number={11}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Komirenko, S. M. and Kim, K. W. and Kochelap, V. A. and Stroscio, M. A.}, year={2001}, month={Aug} }
 @article{komirenko_kim_demidenko_kochelap_stroscio_2000, title={Cerenkov generation of high-frequency confined acoustic phonons in quantum wells}, volume={76}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.126195}, DOI={10.1063/1.126195}, abstractNote={We analyze the Cerenkov emission of high-frequency confined acoustic phonons by drifting electrons in a quantum well. We find that the electron drift can cause strong phonon amplification (generation). A general formula for the gain coefficient α is obtained as a function of the phonon frequency and the structure parameters. The gain coefficient increases sharply in the short-wave region. For the example of a Si/SiGe/Si device, it is shown that the amplification coefficients of the order of hundreds of cm−1 can be achieved in the subterahertz frequency range.}, number={14}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Komirenko, S. M. and Kim, K. W. and Demidenko, A. A. and Kochelap, V. A. and Stroscio, M. A.}, year={2000}, month={Apr}, pages={1869–1871} }
 @article{komirenko_kim_kochelap_fedorov_stroscio_2000, title={Coherent optical phonon generation by the electric current in quantum wells}, volume={77}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.1334653}, DOI={10.1063/1.1334653}, abstractNote={This letter addresses the effect of generation of confined LO phonons by drifting electrons in quantum wells. We have derived a general formula for the phonon increment as a function of phonon wave vector, electron drift velocity, and structure parameters. Numerical estimates of the phonon increment and the phonon lifetimes have shown that AlAs/GaAs/AlAs and GaSb/InSb/GaSb quantum well structures can demonstrate the effect of coherent LO phonon generation by the electric current.}, number={25}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Komirenko, S. M. and Kim, K. W. and Kochelap, V. A. and Fedorov, I. and Stroscio, M. A.}, year={2000}, month={Dec}, pages={4178–4180} }
 @article{komirenko_kim_stroscio_dutta_2000, title={Energy-dependent electron scattering via interaction with optical phonons in wurtzite crystals and quantum wells}, volume={61}, ISSN={0163-1829 1095-3795}, url={http://dx.doi.org/10.1103/PhysRevB.61.2034}, DOI={10.1103/physrevb.61.2034}, abstractNote={A formalism for the calculation of the scattering rate in wurtzite-type crystals and quantum wells (QW's) is developed taking into account features of the optical phonon spectra in an optically anisotropic medium. The electron-scattering rate due to the interaction with infrared/Raman-active polar optical phonons in GaN, bulk material, and heterostructures, is investigated. To determine the dependence of scattering rate on optical anisotropy and dimensionally induced transformation of the phonon spectra, three cases are considered: (a) bulk material with different orientations of the electron wave vector with respect to the optical axis; (b) a system in which bulk phonons interact with electrons confined in a QW; and (c) free-standing and embedded QW's where the effects of confinement of both electron and phonon subsystems are taken into account. It is found that the scattering rate depends weakly on the initial orientation of the electron wave vector. Exceptions are the energy intervals which correspond to the threshold values for emission of both TO-like and LO-like bulk phonons. Our results reveal a complex and strong dependence of the electron-scattering rate on the dispersion of a particular mode. Moreover, this dependence is found to be the main factor which determines electron-phonon scattering in wurtzite heterostructures, in particular, through the relation between phonon phase and group velocities. For the optically anisotropic media considered, the effect of spatial localization of the phonon modes on the scattering rate is found to be as strong as the effect of electron confinement.}, number={3}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Komirenko, S. M. and Kim, K. W. and Stroscio, M. A. and Dutta, M.}, year={2000}, month={Jan}, pages={2034–2040} }
 @article{komirenko_kim_demidenko_kochelap_stroscio_2000, title={Generation and amplification of sub-THz coherent acoustic phonons under the drift of two-dimensional electrons}, volume={62}, ISSN={0163-1829 1095-3795}, url={http://dx.doi.org/10.1103/PhysRevB.62.7459}, DOI={10.1103/physrevb.62.7459}, abstractNote={This paper addresses the \ifmmode \check{C}\else \v{C}\fi{}erenkov emission of high-frequency confined acoustic phonons by drifting electrons in a quantum well. We have found that the electron drift can cause strong phonon amplification (generation). The spectra of the confined modes are calculated and their confinement properties are analyzed. The spectra consist of a set of branches, and for each branch, the confinement effect increases considerably when the phonon wave vector increases. We have studied the coupling between electrons and confined modes and proved that the coupling is a nonmonotonous function of the wave vector for each of the phonon branches. We have obtained a general formula for the gain coefficient as a function of the phonon frequency and the structure parameters. For each of the branches, the amplification takes place in a spectrally separated and quite narrow amplification band in the high-frequency range. For the example of p-doped Si/SiGe/Si heterostructures it is shown that the amplification coefficients of the order of hundreds of ${\mathrm{cm}}^{\ensuremath{-}1}$ can be achieved in the sub-THz frequency range.}, number={11}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Komirenko, S. M. and Kim, K. W. and Demidenko, A. A. and Kochelap, V. A. and Stroscio, M. A.}, year={2000}, month={Sep}, pages={7459–7469} }
 @article{bergman_dutta_stroscio_komirenko_nemanich_eiting_lambert_kwon_dupuis_2000, title={Photoluminescence and recombination mechanisms in GaN/Al0.2Ga0.8N superlattice}, volume={76}, ISSN={["0003-6951"]}, DOI={10.1063/1.126225}, abstractNote={A detailed study of photoluminescence (PL) of GaN(1 nm)/Al0.2Ga0.8N(3.3 nm) twenty periods superlattice grown via metal-organic chemical vapor deposition is presented. The dependence of the PL emission energy, linewidth, and intensity on temperature, in the low temperature regime, is consistent with recombination mechanisms involving bandtail states attributed to a small degree of interfacial disorder. The activation energy of the nonradiative centers in our superlattice agrees well with the value we derive for the width of the tail-state distribution. Moreover, we find that the average phonon energy of the phonons that control the interband PL energy at high temperatures is larger for the superlattice than for a high-quality GaN film. This observation is consistent with model calculations predicting the phonon mode properties of GaN–AlN-based wurtzite heterostructures.}, number={15}, journal={APPLIED PHYSICS LETTERS}, author={Bergman, L and Dutta, M and Stroscio, MA and Komirenko, SM and Nemanich, RJ and Eiting, CJ and Lambert, DJH and Kwon, HK and Dupuis, RD}, year={2000}, month={Apr}, pages={1969–1971} }
 @article{alexson_bergman_dutta_kim_komirenko_nemanich_lee_stroscio_yu_1999, title={Confined phonons and phonon-mode properties of III–V nitrides with wurtzite crystal structure}, volume={263-264}, ISSN={0921-4526}, url={http://dx.doi.org/10.1016/S0921-4526(98)01423-9}, DOI={10.1016/s0921-4526(98)01423-9}, abstractNote={Stimulated by the recent interest in the use of nitride-based III–V wurtzite structures for optoelectronic and electronic devices, this paper reports on the application of the Loudon model for uniaxial crystals to derive the Fröhlich interaction Hamiltonian as well as the electron–optical-phonon scattering rate in wurtzite crystals. This paper also presents experimental analyses of the mode behavior of phonons in wurtzite crystals.}, journal={Physica B: Condensed Matter}, publisher={Elsevier BV}, author={Alexson, D and Bergman, Leah and Dutta, Mitra and Kim, K.W and Komirenko, S and Nemanich, Robert J and Lee, B.C and Stroscio, Michael A and Yu, SeGi}, year={1999}, month={Mar}, pages={510–513} }
 @article{komirenko_kim_stroscio_dutta_1999, title={Dispersion of polar optical phonons in wurtzite quantum wells}, volume={59}, ISSN={0163-1829 1095-3795}, url={http://dx.doi.org/10.1103/PhysRevB.59.5013}, DOI={10.1103/physrevb.59.5013}, abstractNote={Dispersion relations for polar optical phonon modes in wurtzite quantum wells (QW's) are obtained in the framework of the dielectric continuum model. It is found that anisotropy of the dielectric medium causes a number of qualitative peculiarities in the phonon spectra. Among these are the absence of the proper confinement for the oscillatory waves located in the QW, inversion of the order of symmetric and antisymmetric quasiconfined optical modes, formation of the finite energy intervals where such confined modes---which are found to be dispersive---can exist, penetration of the half-space phonons into the QW, etc. Some additional peculiarities, such as appearance of propagating modes, strong dispersion of long-wavelength half-space modes, and reduction of the number of interface modes, arise as a result of overlapping characteristic phonon frequencies of the surrounding material and the material of QW. Predicted phonon behavior leads to the conclusion that dependence of dielectric properties of ternary-binary low-dimensional wurtzite heterostructures on composition can serve as a powerful tool for the purposes of phonon spectrum engineering. In order to illustrate these results, the optical phonon spectra are calculated for an ${\mathrm{Al}}_{0.15}{\mathrm{Ga}}_{0.85}\mathrm{N}/\mathrm{GaN}/{\mathrm{Al}}_{0.15}{\mathrm{Ga}}_{0.85}\mathrm{N} \mathrm{QW},$ an $\mathrm{AlN}/\mathrm{GaN}/\mathrm{AlN} \mathrm{QW},$ and for a $\mathrm{GaN}$ dielectric slab.}, number={7}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Komirenko, S. M. and Kim, K. W. and Stroscio, M. A. and Dutta, M.}, year={1999}, month={Feb}, pages={5013–5020} }
 @article{komirenko_kim_kochelap_dutta_stroscio_1999, title={Phase instability and electron-assisted renormalization of acoustic phonon spectrum in free-standing quantum wires}, volume={263-264}, ISSN={0921-4526}, url={http://dx.doi.org/10.1016/S0921-4526(98)01253-8}, DOI={10.1016/s0921-4526(98)01253-8}, abstractNote={Abstract In this paper we consider the possibility of a Peierls phase transition for a system of one-dimensional electrons and acoustic phonons confined in a free-standing quantum wire (FSQWI). We assume that electrons and phonons are coupled via the deformation potential interaction. The dispersion relation for this system is derived taking into account the role of electrostatic effects. The Peierls phase transition to the state characterized by periodic lattice deformation (PLD) is obtained in the high-permittivity limit. The formalism developed in this paper facilitates investigation of the renormalized acoustic phonon spectrum and predicts the possibility of the Peierls transition in FSQWIs fabricated from semiconductor materials with large permittivity.}, journal={Physica B: Condensed Matter}, publisher={Elsevier BV}, author={Komirenko, S.M. and Kim, K.W. and Kochelap, V.A. and Dutta, Mitra and Stroscio, Michael A.}, year={1999}, month={Mar}, pages={522–525} }