Experimental evidences for reducing Mg activation energy in high Al-content AlGaN alloy by Mg δ doping in (AlN)/(GaN) superlattice.

P-type doping in high Al-content AlGaN alloys is a main challenge for realizing AlGaN-based deep ultraviolet optoelectronics devices. According to the first-principles calculations, Mg activation energy may be reduced so that a high hole concentration can be obtained by introducing nanoscale (AlN)/(GaN) superlattice (SL) in AlGaN disorder alloy. In this work, experimental evidences were achieved by analyzing Mg doped high Al-content AlGaN alloys and Mg doped AlGaN SLs as well as Mg δ doped AlGaN SLs. Mg acceptor activation energy was significantly reduced from 0.378 to 0.331 eV by using Mg δ doping in SLs instead of traditional doping in alloys. This new process was confirmed to be able to realize high p-type doping in high Al-content AlGaN.