P-GaN Ohmic Contacts For GaN-Based Laser Diodes

As the development of GaN-based semiconductor materials, GaN-based devices are being used as much as possible. However, there are numerous challenges in the process of making devices, the low resistance ohmic contact to p-GaN is one of the crucial issues to be solved. The main content as follows:1. We investigate the specific contact resistance of Ni/Au ohmic contact on p-GaN as a function of anneal temperature, anneal time and anneal atmosphere, the lowest specific contact resistance of Au(5nm)/Ni(5nm)/p-GaN was achieved at 500℃. in the atmosphere of N₂∶O₂=3∶1 for 5 minutes. The effect of the aqua regia solution on ohmic contact property of p-GaN was investigated. After aqua regia treatment the specific contact resistance of Au/Ni/p-GaN was improved from 8×10^-3Ω·cm² to2.9×10^-4Ω·cm².2. The electrical properties of Ni/Ag ohmic contact on p-GaN at different temperature, various atmosphere, different time and different thick of metal were investigated. The lowest specific contact resistance 2.5×10^-4Ω·cm² of Ag(120nm)/Ni(5nm)/p-GaN was obtained at 550℃ in O₂ for 1 minute.