Abstract
Random alloy fluctuations significantly affect the electronic, optical, and transport properties of (In,Ga)N-based optoelectronic devices. Transport calculations accounting for alloy fluctuations currently use a combination of modified continuum-based models, which neglect to a large extent atomistic effects. In this work, we present a model that bridges the gap between atomistic theory and macroscopic transport models. To do so, we combine atomistic tight-binding theory and continuum-based drift–diffusion solvers, where quantum corrections are included via the localization landscape method. We outline the ingredients of this framework in detail and present first results for uni-polar electron transport in single and multi- (In,Ga)N quantum well systems. Overall, our results reveal that both random alloy fluctuations and quantum corrections significantly affect the current–voltage characteristics of uni-polar electron transport in such devices. However, our investigations indicate that the importance of quantum corrections and random alloy fluctuations can be different for single and multi-quantum well systems.
Highlights
III-nitride (III-N)-based quantum well (QW) structures are at the heart of modern short wavelength light emitting diodes (LEDs).[1,2] Here, (In,Ga)N/GaN multi-QWs (MQWs) are used to realize devices operating in the visible part of the spectrum
Our results reveal that both random alloy fluctuations and quantum corrections significantly affect the current–voltage characteristics of uni-polar electron transport in such devices
We apply the developed framework to unipolar, n-doped/intrinsic/n-doped (n-i-n), (In,Ga)N/GaN-based devices: We analyze the impact of random alloy fluctuations and quantum corrections introduced by localization landscape theory (LLT) on the I–V curves of such scitation.org/journal/jap
Summary
III-nitride (III-N)-based quantum well (QW) structures are at the heart of modern short wavelength light emitting diodes (LEDs).[1,2] Here, (In,Ga)N/GaN multi-QWs (MQWs) are used to realize devices operating in the visible part of the spectrum. Based on such a distribution, the local In content is determined by using averaging procedures on the underlying grid Equipped with this information, continuumbased strain and built-in field calculations are performed, which can be used to generate an “energy landscape” (conduction and valence band edges/confining potential), mainly in the framework of a single-band effective mass approximation (EMA). It is important to note that such an approach relies on (i) identifying an interpolation procedure for the local alloy content, (ii) the knowledge of how related material parameters change with composition locally, and (iii) assuming that bulk parameters can be used locally to obtain strain and built-in field effects It assumes that even when including random alloy fluctuations, the modified continuum-based single-band EMA describes the electronic structure of this complicated system accurately.
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