@inproceedings{baek_dutta_bhattacharya_2011, title={Characterization of a three-phase dual active bridge DC/DC converter in Wye-Delta connection for a high frequency and high power applications}, booktitle={2011 IEEE Energy Conversion Congress and Exposition (ECCE)}, author={Baek, S. and Dutta, S. and Bhattacharya, S.}, year={2011}, pages={4183–4188} }
 @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{stroscio_dutta_kahn_kim_2001, title={Continuum model of optical phonons in a nanotube}, volume={29}, ISSN={0749-6036}, url={http://dx.doi.org/10.1006/spmi.2001.0980}, DOI={10.1006/spmi.2001.0980}, abstractNote={The properties of nanotubes are of intense current interest due, in part, to the discovery of the carbon nanotube. In this paper, the optical phonons are modeled for a nanotube by treating the nanotube as a continuum medium. A quantization prescription is applied to facilitate the first determination of the quantum-mechanical normalizations of selected optical phonon modes. It is shown that normalization of the lowest azimuthal mode may be determined analytically. The deformation potentials describing carrier optical-phonon scattering are readily determined from these normalized continuum modes.}, number={6}, journal={Superlattices and Microstructures}, publisher={Elsevier BV}, author={Stroscio, Michael A. and Dutta, Mitra and Kahn, Daniel and Kim, Ki Wook}, year={2001}, month={Jun}, pages={405–409} }
 @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{alexson_bergman_nemanich_dutta_stroscio_parker_bedair_el-masry_adar_2001, title={Ultraviolet raman study of A(1)(LO) and E-2 phonons in InxGa1-xN alloys}, volume={89}, ISSN={["0021-8979"]}, DOI={10.1063/1.1330760}, abstractNote={We report on ultraviolet Raman spectroscopy of InxGa1−xN thin films grown on sapphire by metal-organic chemical vapor deposition. The A1(LO) and E2 phonon mode behavior was investigated over a large compositional range (0<x<0.50). Compelling evidence is presented for one-mode behavior for the A1(LO) phonon, and data suggestive of two-mode behavior are presented for the E2 phonon.}, number={1}, journal={JOURNAL OF APPLIED PHYSICS}, author={Alexson, D and Bergman, L and Nemanich, RJ and Dutta, M and Stroscio, MA and Parker, CA and Bedair, SM and El-Masry, NA and Adar, F}, year={2001}, month={Jan}, pages={798–800} }
 @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{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} }
 @article{bergman_alexson_nemanich_dutta_stroscio_balkas_davis_1999, title={Phonon dynamics and lifetimes of AlN and GaN crystallites}, volume={4S1}, DOI={10.1557/s1092578300003422}, abstractNote={The quasi-LO and quasi-TO modes of AlN crystallite were investigated. The analysis indicates that the Raman mode behavior concurs with Loudons’ model of mode-mixing in wurtzite (WZ) structure crystals which is due to the long-range electrostatic field. Phononlifetimes of GaN and AlN crystallites were studied via Raman lineshape. It was found that the low energy E2 mode lifetime is about an order of magnitude longer than that of the other modes, and that impurities impact significantly the phonon-lifetimes.}, number={G6.65}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Bergman, L. and Alexson, D. and Nemanich, R. J. and Dutta, M. and Stroscio, M. A. and Balkas, C. and Davis, R. F.}, year={1999} }
 @article{bergman_alexson_murphy_nemanich_dutta_stroscio_balkas_shin_davis_1999, title={Raman analysis of phonon lifetimes in AlN and GaN of wurtzite structure}, volume={59}, ISSN={["1550-235X"]}, DOI={10.1103/physrevb.59.12977}, abstractNote={Raman analyses of the lifetimes of phonons in GaN and AlN crystallites of wurtzite structure are presented. In order to ensure the accuracy of the measurement of the phonon lifetimes, an experimental procedure to eliminate the broadening due to the finite slit width was performed. The lifetime analyses indicate that the phonon lifetimes in AlN as well as in GaN fall into two main time regimes: a relatively long time of the ${E}_{2}^{1}$ mode and much shorter times of the ${E}_{2}^{2},$ $E1(\mathrm{TO}),$ and $A1(\mathrm{TO})$ modes. The lifetimes of the ${E}_{2}^{1},$ ${E}_{2}^{2},$ $E1(\mathrm{TO}),$ $A1(\mathrm{TO}),$ and $A1(\mathrm{LO})$ modes of an high-quality AlN crystallite are 4.4, 0.83, 0.91, 0.76, and 0.45 ps, respectively. Moreover, the lifetime of the $A1(\mathrm{LO})$ mode found in this study is consistent with the current phonon-decay model of that mode in wurtzite structure materials. The lifetimes of ${E}_{2}^{1},$ ${E}_{2}^{2},$ $E1(\mathrm{TO}),$ and $A1(\mathrm{TO})$ of a GaN crystallite were found to be 10.1, 1.4, 0.95, and 0.46 ps, respectively. The $A1(\mathrm{LO})$ mode in the GaN was not observed and its absence is attributed to plasmon damping. The lifetime shortening due to impurities was also studied: the lifetimes of the Raman modes of an AlN crystallite, which contains about two orders of magnitude more Si and C impurities relative to the concentration of the high-quality crystallite were found to be 50% shorter.}, number={20}, journal={PHYSICAL REVIEW B}, author={Bergman, L and Alexson, D and Murphy, PL and Nemanich, RJ and Dutta, M and Stroscio, MA and Balkas, C and Shin, H and Davis, RF}, year={1999}, month={May}, pages={12977–12982} }
 @article{bergman_dutta_balkas_davis_christman_alexson_nemanich_1999, title={Raman analysis of the E1 and A1 quasi-longitudinal optical and quasi-transverse optical modes in wurtzite AlN}, volume={85}, ISSN={["0021-8979"]}, DOI={10.1063/1.369712}, abstractNote={This article presents a study of the quasi-longitudinal optical and quasi-transverse optical modes in wurtzite AlN which originate from the interaction of phonons belonging to the A1 and E1 symmetry groups. In order to analyze the allowed quasi as well as pure Raman modes, the modes were observed in a rotating crystallographic coordinate system, and the Raman tensors of the wurtzite crystal structure were calculated as a function of the crystallographic rotation. The frequencies of the quasimodes of wurtzite AlN were also analyzed in terms of the interaction of the polar phonons with the long range electrostatic field model. The experimental values of the Raman frequencies of the quasiphonons concur with these expected from the model, implying that the long range electrostatic field dominates the short range forces for polar phonons in AlN.}, number={7}, journal={JOURNAL OF APPLIED PHYSICS}, author={Bergman, L and Dutta, M and Balkas, C and Davis, RF and Christman, JA and Alexson, D and Nemanich, RJ}, year={1999}, month={Apr}, pages={3535–3539} }
 @article{belenky_dutta_b. gorfinkel_haddad_iafrate_kim_kisin_luryi_stroscio_sun_et al._1999, title={Tailoring of optical phonon modes in nanoscale semiconductor structures: role of interface-optical phonons in quantum-well lasers}, volume={263-264}, ISSN={0921-4526}, url={http://dx.doi.org/10.1016/S0921-4526(98)01410-0}, DOI={10.1016/S0921-4526(98)01410-0}, abstractNote={This paper discusses the concept of enhancing semiconductor laser performance through tailoring of scattering rates of confined polar-optical phonons. Studies of optically pumped intersubband scattering in coupled quantum-well lasers have demonstrated that interface-phonon-assisted transitions are important in such structures; furthermore, simple analytical expressions have been derived that indicate the importance of interface-phonon scattering in quantum-well lasers. These calculations reveal that the interface-phonon-assisted transitions are dominant for small quantum well dimensions of approximately 40 Å; such dimensions are typical of novel lasers including both the unipolar quantum cascade laser and the tunneling injection laser. Recent numerical calculations have confirmed these effects and have extended them to indicate how confined and interface phonons also affect critical laser properties such as optical gain. The application of confined phonon effects to intersubband lasers is one of the most important applications of confined-phonon physics to the present time.}, journal={Physica B: Condensed Matter}, publisher={Elsevier BV}, author={Belenky, Gregory and Dutta, Mitra and B. Gorfinkel, Vera and Haddad, George I. and Iafrate, G.J. and Kim, K.W. and Kisin, Mikhail and Luryi, Serge and Stroscio, Michael A. and Sun, J.P. and et al.}, year={1999}, month={Mar}, pages={462–465} }
 @misc{iafrate_he_dutta_stroscio_1998, title={Field controlled current modulators based on tunable barrier strengths}, volume={5705824}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Iafrate, G. J. and He, J. and Dutta, M. and Stroscio, M. A.}, year={1998} }
 @article{yu_kim_bergman_dutta_stroscio_zavada_1998, title={Long-wavelength optical phonons in ternary nitride-based crystals}, volume={58}, ISSN={0163-1829 1095-3795}, url={http://dx.doi.org/10.1103/PhysRevB.58.15283}, DOI={10.1103/physrevb.58.15283}, abstractNote={Phonon modes in column-III--nitride ternary semiconductors are investigated theoretically within the modified random-element isodisplacement model. It is found that ${A}_{1}$ and ${E}_{1}$ branches of optical phonons in wurtzite ${\mathrm{Ga}}_{x}{\mathrm{Al}}_{1\ensuremath{-}x}\mathrm{N}$ and ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}$ exhibit one-mode behavior. This result is explained by the fact that atomic mass of nitrogen is much smaller than those of other atoms.}, number={23}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Yu, SeGi and Kim, K. W. and Bergman, Leah and Dutta, Mitra and Stroscio, Michael A. and Zavada, John M.}, year={1998}, month={Dec}, pages={15283–15287} }
 @article{lee_kim_stroscio_dutta_1998, title={Optical-phonon confinement and scattering in wurtzite heterostructures}, volume={58}, ISSN={0163-1829 1095-3795}, url={http://dx.doi.org/10.1103/PhysRevB.58.4860}, DOI={10.1103/physrevb.58.4860}, abstractNote={We investigate Fr\"ohlich-like electron--optical-phonon interactions in wurtzite structures with single and double heterointerfaces based on the macroscopic dielectric continuum model and the uniaxial model. In addition to confined (for the case of double interfaces), interface, and half-space optical phonon modes as expected from the analogy with zinc-blende structures, propagating modes may exist in wurtzite heterosystems due to anisotropic phonon dispersion. This is especially the case when the dielectric properties of the adjacent heterostructure materials do not differ substantially. The dispersion relations and the interaction Hamiltonians for each of these modes are derived.}, number={8}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Lee, B. C. and Kim, K. W. and Stroscio, M. A. and Dutta, M.}, year={1998}, month={Aug}, pages={4860–4865} }
 @book{dutta_stroscio_1998, title={Quantum-based electronic devices and systems}, ISBN={9810237006}, publisher={Singapore; River Edge, NJ: World Scientific}, author={Dutta, M. and Stroscio, M. A.}, year={1998} }
 @article{lee_kim_dutta_stroscio_1997, title={Electron–optical-phonon scattering in wurtzite crystals}, volume={56}, ISSN={0163-1829 1095-3795}, url={http://dx.doi.org/10.1103/PhysRevB.56.997}, DOI={10.1103/physrevb.56.997}, abstractNote={We present Fr\"ohlich-like electron--optical-phonon interaction Hamiltonian for wurtzite crystals in the long-wavelength limit based on the macroscopic dielectric continuum model and the uniaxial model. In general, the optical-phonon branches support mixed longitudinal and transverse modes due to the anisotropy. We calculate electron scattering rate due to the optical phonons in the bulk wurtzite GaN and demonstrate that the scattering rate due to transverselike phonon processes can be strongly enhanced over a range of angles with respect to the $c$ axis. For the case of longitudinal-like modes, the anisotropy is small and the result is almost the same as that obtained with the cubic Fr\"ohlich Hamiltonian.}, number={3}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Lee, B. C. and Kim, K. W. and Dutta, M. and Stroscio, M. A.}, year={1997}, month={Jul}, pages={997–1000} }
 @article{bergman_bremser_perry_davis_dutta_nemanich_1997, title={Raman analysis of the configurational disorder in AlxGa1-xN films}, volume={71}, ISSN={["0003-6951"]}, DOI={10.1063/1.119367}, abstractNote={Raman analysis of the E2 mode of AlxGa1−xN in the composition range 0⩽x⩽1 is presented. The line shape was observed to exhibit a significant asymmetry and broadening toward the high energy range. The spatial correlation model is discussed, and is shown to account for the line shape. The model calculations also indicate the lack of a long-range order in the chemical vapor deposition alloys. These results were confirmed by x-ray scattering: the relative intensity of the superlattice line was found to be negligible. The line broadening of the E2 mode was found to exhibit a maximum at a composition x≅0.5 indicative of a random disordered alloy system.}, number={15}, journal={APPLIED PHYSICS LETTERS}, author={Bergman, L and Bremser, MD and Perry, WG and Davis, RF and Dutta, M and Nemanich, RJ}, year={1997}, month={Oct}, pages={2157–2159} }