Materials Growth And Device Fabrication Of GaN-based Blue LED On Silicon Substrate

GaN-based nitrides as a wide band gap semiconductor has attracted more and more attention and advanced rapidly, mainly due to its promising applications in short wavelength light-emitting devices, short wavelength lasers, ultraviolet detectors, as well as high temperature, high frequency and high power electronic devices. Sapphire and SiC are the common substrates for GaN expitaxy for it's difficult to grow GaN bulk single crystal. But sapphire is not conductive and hard to cleave, and SiC is very expensive. Compared with sapphire and SiC, silicon is another promising substrate for GaN growth because of its low cost, large size, high electrical and thermal conductivities and the potential application in the integration of optoelectronic and microelectronic devices.In this thesis, GaN and its ternary were grown by Thomas Swan 7 × 2" MOCVD systems. We carried out a detailed study of GaN epitaxy and fabrication of GaN-based light-emitting diodes on silicon substrate. Some encouraging results are following as:1. Three kinds of process of Al-predeposition on Si(111) substrate were investigated. This research indicated that the deposition case of Al on Si substrate will effect the quality and surface of GaN epilayer greatly. The GaN epilayer will be worse with a bad Al-predeposition case than without Al-predeposition. The DCXRD and TEM results show that the formation of SiN_x at the Si/Al interface was suppressed, and good quality GaN film was obtained with Al-predeposition on silicon substrate in situ in chamber.2. The influence of the growth thickness of A1N buffer layer on the properties of GaN epilayer was studied. The optimum thickness of A1N buffer has a range. Ga droplet meltback on the sillicon substrate was found with thin A1N buffer, and cracks were observed on the GaN epilayer surface with thick A1N buffer. This results show that A1N buffer with appropriate thickness can suppress Ga droplet...