@article{jin_mullen_kim_2016, title={Highly anisotropic electronic transport properties of monolayer and bilayer phosphorene from first principles}, volume={109}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4960526}, DOI={10.1063/1.4960526}, abstractNote={The intrinsic carrier transport dynamics in phosphorene is theoretically examined. Utilizing a density functional theory treatment, the low-field mobility and the saturation velocity are characterized for both electrons and holes in the monolayer and bilayer structures. The analysis clearly elucidates the crystal orientation dependence manifested through the anisotropic band structure and the carrier-phonon scattering rates. In the monolayer, the hole mobility in the armchair direction is estimated to be approximately five times larger than in the zigzag direction at room temperature (460 cm2/V s vs. 90 cm2/V s). The bilayer transport, on the other hand, exhibits a more modest anisotropy with substantially higher mobilities (1610 cm2/V s and 760 cm2/V s, respectively). The calculations on the conduction-band electrons indicate a comparable dependence while the characteristic values are generally smaller by about a factor of two. The variation in the saturation velocity is found to be less pronounced. With the anticipated superior performance and the diminished anisotropy, few-layer phosphorene offers a promising opportunity particularly in p-type applications.}, number={5}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Jin, Zhenghe and Mullen, Jeffrey T. and Kim, Ki Wook}, year={2016}, month={Aug}, pages={053108} }
 @article{jin_nori_lee_kumar_wu_prater_kim_narayan_2015, title={Strain induced room temperature ferromagnetism in epitaxial magnesium oxide thin films}, volume={118}, number={16}, journal={Journal of Applied Physics}, author={Jin, Z. H. and Nori, S. and Lee, Y. F. and Kumar, D. and Wu, F. and Prater, J. T. and Kim, K. W. and Narayan, J.}, year={2015} }
 @article{yu_hu_su_huang_liu_jin_purezky_geohegan_kim_zhang_et al._2014, title={Equally Efficient Interlayer Exciton Relaxation and Improved Absorption in Epitaxial and Nonepitaxial MoS2/WS2 Heterostructures}, volume={15}, ISSN={1530-6984 1530-6992}, url={http://dx.doi.org/10.1021/nl5038177}, DOI={10.1021/nl5038177}, abstractNote={Semiconductor heterostructures provide a powerful platform to engineer the dynamics of excitons for fundamental and applied interests. However, the functionality of conventional semiconductor heterostructures is often limited by inefficient charge transfer across interfaces due to the interfacial imperfection caused by lattice mismatch. Here we demonstrate that MoS(2)/WS(2) heterostructures consisting of monolayer MoS(2) and WS(2) stacked in the vertical direction can enable equally efficient interlayer exciton relaxation regardless the epitaxy and orientation of the stacking. This is manifested by a similar 2 orders of magnitude decrease of photoluminescence intensity in both epitaxial and nonepitaxial MoS(2)/WS(2) heterostructures. Both heterostructures also show similarly improved absorption beyond the simple superimposition of the absorptions of monolayer MoS(2) and WS(2). Our result indicates that 2D heterostructures bear significant implications for the development of photonic devices, in particular those requesting efficient exciton separation and strong light absorption, such as solar cells, photodetectors, modulators, and photocatalysts. It also suggests that the simple stacking of dissimilar 2D materials with random orientations is a viable strategy to fabricate complex functional 2D heterostructures, which would show similar optical functionality as the counterpart with perfect epitaxy.}, number={1}, journal={Nano Letters}, publisher={American Chemical Society (ACS)}, author={Yu, Yifei and Hu, Shi and Su, Liqin and Huang, Lujun and Liu, Yi and Jin, Zhenghe and Purezky, Alexander A. and Geohegan, David B. and Kim, Ki Wook and Zhang, Yong and et al.}, year={2014}, month={Dec}, pages={486–491} }
 @misc{lee_punugupati_wu_jin_narayan_schwartz_2014, title={Evidence for topological surface states in epitaxial Bi2Se3 thin film grown by pulsed laser deposition through magneto-transport measurements}, volume={18}, ISSN={["1879-0348"]}, DOI={10.1016/j.cossms.2014.07.001}, abstractNote={We report epitaxial growth via domain matching epitaxy of Bi2Se3 thin films on Al2O3 (0 0 0 1) substrates with over 13% lattice misfit and critical thickness less than one monolayer. X-ray and electron diffraction patterns confirm that the layers are epitaxial with (0 0 0 1) Bi2Se3 || (0 0 0 1) Al2O3 and [21¯1¯0] Bi2Se3 || [21¯1¯0] Al2O3 (or) [21¯1¯0] Bi2Se3 || [112¯0] Al2O3 without the presence of an interfacial pseudomorphic layer. X-ray photoemission spectroscopy reveals that the films are Se-deficient, in agreement with electrical transport data showing n-type carriers and metallic behavior. Magneto-resistance (MR) measurements show a cusp feature corresponding to weak antilocalization and linear-MR shows a non-saturating trend up to 9 T. These results suggest topological surface states in PLD-grown Bi2Se3 films.}, number={5}, journal={CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE}, author={Lee, Y. F. and Punugupati, S. and Wu, F. and Jin, Z. and Narayan, J. and Schwartz, J.}, year={2014}, month={Oct}, pages={279–285} }
 @article{mai_semenov_barrette_yu_jin_cao_kim_gundogdu_2014, title={Exciton valley relaxation in a single layer ofWS2measured by ultrafast spectroscopy}, volume={90}, ISSN={1098-0121 1550-235X}, url={http://dx.doi.org/10.1103/PhysRevB.90.041414}, DOI={10.1103/physrevb.90.041414}, abstractNote={We measured the lifetime of optically created valley polarization in single layer WS2 using transient absorption spectroscopy. The electron valley relaxation is very short (< 1ps). However the hole valley lifetime is at least two orders of magnitude longer and exhibits a temperature dependence that cannot be explained by single carrier spin/valley relaxation mechanisms. Our theoretical analysis suggests that a collective contribution of two potential processes may explain the valley relaxation in single layer WS2. One process involves direct scattering of excitons from K to K' valleys with a spin flip-flop interaction. The other mechanism involves scattering through spin degenerate Gamma valley. This second process is thermally activated with an Arrhenius behavior due to the energy barrier between Gamma and K valleys.}, number={4}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Mai, Cong and Semenov, Yuriy G. and Barrette, Andrew and Yu, Yifei and Jin, Zhenghe and Cao, Linyou and Kim, Ki Wook and Gundogdu, Kenan}, year={2014}, month={Jul} }
 @article{kong_jin_kim_2014, title={Hot-Electron Transistors for Terahertz Operation Based on Two-Dimensional Crystal Heterostructures}, volume={2}, ISSN={2331-7019}, url={http://dx.doi.org/10.1103/PhysRevApplied.2.054006}, DOI={10.1103/physrevapplied.2.054006}, abstractNote={The authors explore the feasibility of ultrahigh-frequency devices by utilizing the unique features of two-dimensional (2D) crystals. These materials range from gapless semimetals to wide-band-gap insulators, and a number of them ($e.g.$ hexagonal boron nitride and transition metal dichalcogenides) can be integrated seamlessly with graphene, without causing defects, interfacial scattering centers, or degradation of properties. A detailed theoretical analysis indicates the potential for 2D crystal heterostructures that could process information at rates well over a terahertz--several times the current technological limit.}, number={5}, journal={Physical Review Applied}, publisher={American Physical Society (APS)}, author={Kong, Byoung Don and Jin, Zhenghe and Kim, Ki Wook}, year={2014}, month={Nov} }
 @article{jin_li_mullen_kim_2014, title={Intrinsic transport properties of electrons and holes in monolayer transition-metal dichalcogenides}, volume={90}, ISSN={1098-0121 1550-235X}, url={http://dx.doi.org/10.1103/PhysRevB.90.045422}, DOI={10.1103/physrevb.90.045422}, abstractNote={Intrinsic electron- and hole-phonon interactions are investigated in monolayer transition-metal dichalcogenides $M{X}_{2}$ (M=Mo, W; X=S, Se) based on a density functional theory formalism. Due to their structural similarities, all four materials exhibit qualitatively comparable scattering characteristics with the acoustic phonons playing a dominant role near the conduction and valence band extrema at the K point. However, substantial differences are observed quantitatively leading to disparate results in the transport properties. Of those considered, ${\mathrm{WS}}_{2}$ provides the best performance for both electrons and holes with high mobilities and saturation velocities in the full-band Monte Carlo analysis of the Boltzmann transport equation. It is also found that monolayer $M{X}_{2}$ crystals with an exception of ${\mathrm{MoSe}}_{2}$ generally show hole mobilities comparable to or even larger than the value for bulk silicon at room temperature, suggesting a potential opportunity in p-type devices. The analysis is extended to estimate the effective deformation potential constants for a simplified treatment as well.}, number={4}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Jin, Zhenghe and Li, Xiaodong and Mullen, Jeffrey T. and Kim, Ki Wook}, year={2014}, month={Jul} }
 @article{li_mullen_jin_borysenko_buongiorno nardelli_kim_2013, title={Intrinsic electrical transport properties of monolayer silicene and MoS2from first principles}, volume={87}, ISSN={1098-0121 1550-235X}, url={http://dx.doi.org/10.1103/PhysRevB.87.115418}, DOI={10.1103/physrevb.87.115418}, abstractNote={Article on intrinsic electrical transport properties of monolayer silicene and MoS₂ from first principles.}, number={11}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Li, Xiaodong and Mullen, Jeffrey T. and Jin, Zhenghe and Borysenko, Kostyantyn M. and Buongiorno Nardelli, M. and Kim, Ki Wook}, year={2013}, month={Mar} }