金属/氮化物肖特基势垒和欧姆接触研究进展

Progress of Investigation on the Schottky Barrier and Ohmic Contacts at Metal/III Nitride Interface

金属 /氮化物肖特基势垒和欧姆接触是蓝紫光光学器件及高温大功率电子器件中的关键工艺。氮化物半导体是一种极性材料 ,表面态密度较低 ,费米能级钉扎效应较弱 ,表面处理能显著影响接触特性。样品表面的沾污和氧化层也会使接触特性显著退化。宽禁带材料的杂质离化能高 ,重掺杂比较困难。深能级陷阱对载流子的俘获效应很强。这些因素都增加了接触的制作难度 ,促使人们寻求新的方案来改进接触特性。文中从金属 /半导体接触的物理模型出发来综述肖特基势垒和欧姆接触的研究进展 ,希望能给器件研究者提供新的思路。

The Schottky barrier and ohmic contacts at metal/Ⅲ-nitride interfaces are the key technology to develop the blue and ultraviolet optical devices and high temperature, high power electronic devices. Ⅲ-nitrides are polar semiconductor with low density of surface states, so that the Fermi level pinning is rather weak and the surface treatments have obvious influence on contact characteristics. The surface contamination and oxidation also deteriorate the contact property. In addition, the high ionization energy of impurity in wide bandgap semiconductors makes difficulties in the raising of density of ionized impurities, and many deep traps may also capture the carriers. All these items increase the degree of difficulty in producing the high-quality contacts, so that it is necessary to find new schemes to improve the contact properties. The physical models to improve these contact properties are summarized in this paper in the hope of providing some new ideas for researchers engaged in devices.