Contact mechanisms and design principles for alloyed Ohmic contacts to p-type GaN
Contact mechanisms and design principles for alloyed Ohmic contacts to p-type GaN
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DOI：
10.1080/14786430410001697306
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发表时间：
2004-08
影响因子：
1.6
通讯作者：
S. Mohammad
中科院分区：
文献类型：
--
作者：
S. Mohammad
研究了p型GaN（p-GaN）合金欧姆接触的接触机理和设计原则。说明性的研究包括双层、三层和四层欧姆接触。几乎所有的接触似乎都遵循所提出的设计原则。优选通过等离子体蚀刻去除表面绝缘层导致金属/半导体势垒降低。这与电子发射一起对于产生低电阻金属/p-GaN接触起着至关重要的作用。由于重掺杂导致的带隙变窄和/或图像力降低也有助于低接触电阻率。适当的金属组合的层厚度、快速热退火（RTA）时间、RTA温度和RTA环境的明智选择可以产生与p-GaN外延层接触的大功函数合金，从而产生稳健的低电阻率的电子发射诱导欧姆接触。研究中提出的接触机构的基本物理和设计原则，对其他接触机构的设计具有指导意义。
Contact mechanisms and design principles of alloyed Ohmic contacts to p-type GaN (p-GaN) are studied. Illustrative studies include bilayer, trilayer and quadrilayer Ohmic contacts. Almost all contacts appear to follow the proposed design principles. The removal of the surface insulating layer, preferably by plasma etching, leads to metal/semiconductor barrier lowering. This, together with thermionic emission, plays a crucial role for yielding low-resistance metal/p-GaN contacts. Band-gap narrowing and/or image force lowering due to heavy doping also contribute to the low contact resistivity. A judicious choice of the layer thicknesses of appropriate metal combination, rapid thermal annealing (RTA) time, RTA temperature and RTA ambient can produce large-work-function alloy(s) in contact with the p-GaN epitaxial layer, creating a robust low-resistivity thermionic-emission-induced Ohmic contact. The fundamental physics of contact mechanisms and design principles proposed in the study is useful for making oth...