Fabrication of N-Electrodes for Deep-Ultraviolet AlGaN LEDs and its Recovery Studies after Plasma Damage

• Main Authors: Chih-Yi Yang, 楊志毅
• Other Authors: 武東星
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/84j4db

碩士 === 國立中興大學 === 材料科學與工程學系所 === 106 === In this thesis, an ammonium hydroxide (NH4OH) mist annealing treatment was used to repair plasma-etched damage n-Al0.58Ga0.42N surface. The effects of annealing temperature and ammonium hydroxide solution concentration on the characteristics of metal/n-Al0.5Ga0.5N and DUV-LEDs optoelectronic performance were investigated in detail. According to the experiment results, the specific contact resistance of the n-Al0.58Ga0.42N without treatment is 5.28×10-3 Ω∙cm2. As the plasma-etched sample treated with NH4OH mist anneal at 900C for 20 minutes with ammonium hydroxide concentration 3.6M, the contact resistance was significantly decrease to 6.18×10-4 Ω∙cm2. From XPS measurement results, the Al 2p and Ga 3d core peaks of n-Al0.5Ga0.5N both shift to higher binding energy after treatment, implying the Al-O and the Ga-O bond formation cause by oxygen doping in n-Al0.5Ga0.5N；From UPS measurement results, the fermi level of the treated sample was found closer to conduction band. This can be explained by the increment of free electron concentration by Oxygen doping. Under the injection current of 350 mA, the forward voltage of DUV-LEDs with NH4OH mist annealing treatment is 6.926 V which is 4.1% smaller than that of the without treatment one (7.212 V). Besides, the EQE of treatment sample gradually increase to 0.61% under the injection current of 20 mA. The experiment results strongly evidence that the specific contact resistance can be significantly reduction after NH4OH mist annealing treatment on plasma-damaged n-AlGaN. This treatment will benefit on the electrical and optoelectrical properties of DUV-LEDs.