Photocurrent Properties of AlGaN/GaN/AlGaN Multilayer Structure on Si

Al_0.2Ga_0.8N/GaN/Al_0.2Ga_0.8N multilayer structures and GaN monolayer structures with AlN as the buffer layers were grown on Si substrates by metal-organic chemical vapor deposition. The photocurrent responses of these structures were measured and analysed. The multilayer structures showed a high response in a narrow range of wavelength. The peak wavelength is located at 365 nm at which the responsivity is as high as 24A/W under 5.5 V bias; this is much higher than the GaN monolayer structure. This high responsivity results mainly from the high polarization electric-field in the GaN layer of the Al_0.2Ga_0.8N/GaN/Al_0.2Ga_0.8N heterostructure.