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/(similar to100 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 Angstrom. 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 Angstrom. Optimal PL emission intensity was obtained for 52 Angstrom a-plane wells compared to 28 Angstrom c-plane wells, revealing the effects of internal fields on quantum well emission. (C) 2004 American Institute of Physics.