Emission enhancement of GaN/AlGaN single-quantum-wells due to screening ofpiezoelectric field

Photoluminescence (PL) enhancement due to the screening of piezoelectric fi eld induced by Si-doping is systematically studied in GaN/AlGaN quantum wel ls (QWs) fabricated by metal organic vapor-phase-epitaxy (MOVPE). The PL en hancement ratio of QWs for Si-doped directly into the wells was much larger than that for doped only into the barrier layers. This result shows that t he crystal quality of the quantum well is not so damaged by heavy Si-doping , which is different from the cases of GaAs or InP material systems. The PL intensity enhancement ratio was especially large for thick wells. The typi cal value of the enhancement ratio was 30 times for a 5 nm-thick single QW. The optimum Si-doping concentration was approximately 4x10(18) cm(-3). Fro m the well width dependence of the PL enhancement ratio and PL peak shift u nder high excitation conditions, we determined that the dominant effect ind ucing the PL enhancement is screening of piezoelectric field in the QWs. Th ese results indicate that Si-doping is very effective for the application o f GaN/AlGaN QWs to optical devices.