The Study Of Annealed Mg Doped GaN And Wet Etching Of GaN

Gallium Nitride (GaN) and its ternary alloys (InGaN, AlGaN) have excellent properties, and the band gap can be adjusted from0.7eV (InN) to6.2eV (AIN), covering from infrared to visible region to ultraviolet. It is widely accepted that GaN and its ternary alloys have great prospect in fabricating shortwave Light Emitting Diode (LED) and Laser Diode (LD). However, the low carrier concentration and large resistance of p type GaN are the bottleneck of GaN in fabricating high power LED and LD. Besides, wet etching of GaN is also an important subject. Wet etching has many advantages, such as simple equipment, convenient operation, nontoxic gases and small damage to GaN sample, so it is a useful supplement to dry etching of GaN. On the two subjects above, this paper contains two parts:1. Mg doped GaN is grown by metal organic chemical vapor deposition (MOCVD), and then annealed in N2ambient at various temperatures. The result of X-Ray Diffraction (XRD) shows the samples have great crystal quality. At the annealing temperature800℃, a sample with carrier concentration6.84×1O17cm-3, resistivity0.73Ω· cm, mobility12.5cm2/(V·s) can be reached. Through the low temperature PL spectrum of as-grown sample, light emission peaks at3.27eV and3.18eV can be seen, which correspond to the transition between shallow donor and Mg acceptor and the transition between shallow donor and MgGa. A blue emission band with peaks at around2.85eV can be seen from the low temperature PL spectrum of the annealed samples, which is the typical blue emission band in Mg doped GaN.2. Unintentional doped GaN and p type GaN are etched by photo enhanced chemical (PEC) etching. The result shows only unintentional doped GaN is etched because the band between GaN and etching liquid is bent to create barrier. By an improved PEC etching method the p type GaN of green LED can be etched and the I-V curve is tested. The cut-in voltage is about2.9V.