Well-width dependence of photoluminescence emission from a-plane GaN/AlGaN multiple quantum wells

This work investigates the room-temperature photoluminescence (PL) characteristics of nonpolar GaN/(∼100 A Al0.16Ga0.84N) multiple quantum wells (MQWs) in comparison to c-plane structures as a function of GaN quantum well width. 10-period a-plane and c-plane MQW structures were simultaneously regrown on the appropriate GaN/sapphire template layers via metalorganic chemical vapor deposition with well widths ranging from 20 to 70 A. The PL emission energy from a-plane MQWs followed a square well trend modeled using self-consistent Poisson–Schrodinger calculations while the c-plane MQW emission showed a significant redshift with increasing well width which is attributed to the quantum-confined Stark effect. Despite a higher dislocation density, the a-plane MQWs exhibit enhanced recombination efficiency as compared to the c-plane wells since well emission is no longer observed for c-plane wells wider than 50 A. Optimal PL emission intensity was obtained for 52 A a-plane wells compared to 28 A c-plane wells, r...

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