[摘要]：A significant stress-relaxation was observed in GaN epilayers by integrating a heavily Si-doped GaN (n(+)-GaN) sacrificial layer in the undoped GaN templates grown on sapphire substrates by metal-organic chemical vapor deposition. Selective GaN growth and electrochemical etching were exploited to achieve embedded air-gaps. Stress-relaxation and its local variations were probed by Raman mapping of high-frequency transverse-optical E-2 (high) phonon mode of GaN. Enhanced In incorporation and improved light emission were observed in InGaN/GaN multi-quantum well visible light emitting diode structures fabricated on stress-relaxed GaN-epilayers with embedded air-gaps. Relevant sources for stress reduction and improved optical emission have been discussed. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4710561]
