Significant Mobility Enhancement in Coupled AlGaN/GaN Quantum Wells considering Inter-Well Distance and Asymmetric Widths

TL;DR

This paper presents a theoretical study showing that coupled asymmetric AlGaN/GaN quantum wells can significantly enhance electron mobility by optimizing inter-well distance, with potential applications in quantum device engineering.

Contribution

The study introduces a comprehensive theoretical framework for optimizing mobility in coupled AlGaN/GaN quantum wells considering inter-well distance and asymmetry.

Findings

Mobility up to 4.5 times higher than single wells at optimal separation.

Mobility surpasses single wells when inter-well distance exceeds 40 Å.

Maximum enhancement observed at cryogenic temperature (77 K).

Abstract

We demonstrate that coupled AlGaN/GaN quantum wells with asymmetric widths ($L_1-L_2<30 $ A achieve up to 4.5 times higher mobility than single wells at optimal separation (d = 100 A). Crucially, mobility surpasses single wells when d>40 A reversing the trend at smaller distances. This enhancement stems from double-layer screening that suppresses remote/background impurities and dislocations, while LO phonon scattering remains unaffected. For identical wells, coupled systems underperform single wells at d<40 A but exceed them beyond this threshold. Peak gains occur at cryogenic temperatures (77 K). Our results provide a robust theoretical framework to optimize mobility in AlGaN/GaN heterostructures, reducing experimental trial-and-error in quantum device engineering.