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用卢瑟福背散射/沟道技术研究了p-GaN上的Ni/Au电极在氧气氛下相同合金温度(500℃)不同合金时间后的微结构演化,以揭示欧姆接触的形成机制.利用背散射随机谱和RUMP模拟程序研究了电极金属之间的互扩散,用沟道谱探测了电极金属中的氧分布.结合不同合金时间下比接触电阻ρc的变化,发现随着合金时间的延长比接触电阻持续降低,在合金时间60s后降低的速度减慢,Au扩散到GaN的表面,在p-GaN上形成外延结构,O向电极内部扩散反应生成NiO对降低ρc起到了关键的作用,表明合金后Ni/Au双层电极中层反转效应已经发生,这种结构变化是形成欧姆接触的有效机制.在相同合金温度(500℃)不同合金时间中,氧气氛中的p-GaN/Ni/Au电极在合金时间为300s时形成的欧姆接触效果最佳.
The microstructure evolution of Ni / Au electrode on p-GaN at different alloy temperatures (500 ℃) under the same oxygen atmosphere was investigated by Rutherford backscattering / channeling technique to reveal the formation mechanism of ohmic contact. Backscattering stochastic spectra and RUMP simulation program were used to study the interdiffusion between the electrode metals and to detect the oxygen distribution in the electrode metals by using the channel spectra.Compared with the change of the contact resistance ρc under different alloy times, it was found that with the extension of the alloy time The specific resistance decreased continuously and the rate of decrease slowed down after 60s of alloy time. Au diffused to the surface of GaN and formed epitaxial structure on p-GaN. The diffusion reaction of O into the electrode generated NiO played a key role in reducing ρc. The results show that the intermediate reversal effect of the Ni / Au bilayer electrode has occurred and this structure change is an effective mechanism to form ohmic contact.Under the same alloy temperature (500 ℃), the p-GaN / Ni / Au electrode at the alloy time of 300s ohmic contact formed the best.