Atomistic description of wave function localization effects in InxGa1-xN alloys and quantum wells

Stefan Schulz; O. Marquardt; C. Coughlan; M. A. Caro; O. Brandt; E. P. O'Reilly

doi:10.1117/12.2084800

16 March 2015 Atomistic description of wave function localization effects in In_xGa_1-xN alloys and quantum wells

Stefan Schulz, O. Marquardt, C. Coughlan, M. A. Caro, O. Brandt, E. P. O'Reilly

Proceedings Volume 9357, Physics and Simulation of Optoelectronic Devices XXIII; 93570C (2015) https://doi.org/10.1117/12.2084800
Event: SPIE OPTO, 2015, San Francisco, California, United States

Abstract

We present a detailed analysis of wave function localization effects in In_xGa_1−xN alloys and quantum wells. Our work is based on density functional theory to analyze the impact of isolated and clustered In atoms on the wave function localization characteristics in In_xGa_1−xN alloys. We address the electronic structure of In_0.25Ga_0.25N/GaN quantum wells by means of an atomistic tight-binding model. Random alloy fluctuations in the quantum well region and well-width fluctuations are explicitly taken into account. The tight-binding model includes strain and built-in field fluctuations arising from the random In distribution. Our density functional theory study reveals increasing hole wave function localization effects when an increasing number of In atoms share the same N atom. We find that these effects are less pronounced for the electrons. Our tight-binding analysis of In_0.25Ga_0.27N/GaN quantum wells also reflects this behavior, revealing strong hole localization effects arising from the random In atom distribution. We also show that the excited hole states are strongly localized over an energy range of approximately 50 meV from the top of the valence band. For the quantum wells considered here we observe that well-width fluctuations lead to electron wave function localization effects.

Citation Download Citation

Stefan Schulz, O. Marquardt, C. Coughlan, M. A. Caro, O. Brandt, and E. P. O'Reilly "Atomistic description of wave function localization effects in In_xGa_1-xN alloys and quantum wells", Proc. SPIE 9357, Physics and Simulation of Optoelectronic Devices XXIII, 93570C (16 March 2015); https://doi.org/10.1117/12.2084800

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