Ag与p型GaP欧姆接触的表面特性分析

在p型GaP表面制作Ag电极,并利用退火环境令金属和半导体的接触界面产生良好的欧姆接触。通过扫描电子显微镜(SEM)、俄歇电子能谱(AES)以及X射线光电子能谱(XPS)的表征分析与对比,研究了不同退火环境对欧姆接触表面特性的影响。结果表明:退火时间过短,获得能量自由移动的原子移动面积小,不利于提高样品表面致密性；退火温度过高,欧姆接触表面的晶粒又容易发生球聚现象,造成样品表面的粗糙程度加剧。另外,在退火过程中,发生的相互扩散、形成化合物和合金相以及氧化反应也会对欧姆接触表面特性产生影响。其中,氧化反应较其他反应更为剧烈,对比接触电阻率的影响更大。因此,适宜的退火环境和有效控制氧化反应是增强欧姆接触性能的关键。

Analysis of the Surface Properties of Ag and p-GaP Ohm Contacts

The Ag electrodes were fabricated on the p-type gap surface, and the annealing environment was used to make good Ohmic contact at the contact interface between the metal and the semiconductor. The influence of different annealing environments on Ohmic contact surface was also investigated by characterization and comparison of scanning electron microscope (SEM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The results show that if the annealing time is too short, the area of atoms moving freely with energy is small, which is not conducive to improving the surface denseness of the sample. And if the annealing temperature is too high, the grains on the Ohmic contact surface are easy to merge, causing the roughness of the sample surface to increase. In addition, during the annealing process, the mutual diffusion, the formation of the compound and the alloy phase, and the oxidation reaction will also affect the Ohmic contact surface characteristics. Among them, the oxidation reaction is more intense than other reactions and has a greater effect than the contact resistivity. Therefore, a suitable annealing environment and effective control of the oxidation reaction are key to enhance the Ohmic contact performance.