Contact mechanisms and design principles for alloyed ohmic contacts to n-GaN
Contact mechanisms and design principles for alloyed ohmic contacts to n-GaN
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DOI：
10.1063/1.1712016
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发表时间：
2004-06-15
影响因子：
3.2
通讯作者：
Mohammad, SN
中科院分区：
文献类型：
--
作者：
Mohammad, SN
研究了氮化氮化镓合金欧姆接触机理和设计原则。研究中同时考虑了隧道接触和热离子接触。隧道触点包括Ti/Al/Ti/Au、Ti/Al/Ni/Au、Ti/Al/Pd/Au、(Ta,Ti)/Ni/Au、Ti/Al/Mo/Au和Ti/Au/Pd/Au，热离子触点包括Ni/Au触点。所提出的设计原则正确地规定了所有这些触点的特性。目前认为，隧穿作用是隧道触头低电阻率的主要机制。目前的研究表明，隧道效应和热离子发射对这些触点的低电阻率同样重要。由于大量掺杂导致的带隙缩小和/或成像力降低也有助于降低这些触点的电阻率。本研究的一个令人兴奋的特点是观察到在大功功能金属的适当组合退火过程中形成的非常低功函数的金属间合金。如果退火条件优化，触点变得非常坚固，热稳定，低电阻，热离子发射是电子传递的主要机制。这一观察结果非常有希望，并有可能为不同类型的热离子接触开辟道路。讨论了设计原理的基本物理原理。这些原则是足够普遍的，至少适用于其他III-V氮化物。(C) 2004年美国物理研究所。
Contact mechanisms and design principles of alloyed ohmic contacts to n-GaN are investigated. For the investigation, both tunnel contacts and thermionic contacts are considered. While the tunnel contacts include the Ti/Al/Ti/Au, Ti/Al/Ni/Au, Ti/Al/Pd/Au, (Ta,Ti)/Ni/Au, Ti/Al/Mo/Au, and Ti/Au/Pd/Au contacts, the thermionic contacts include the Ni/Au contacts. The proposed design principles correctly dictate the characteristics of all these contacts. At present, tunneling is believed to be the primary mechanism for low resistivity of the tunnel contacts. The present study demonstrates that both tunneling and thermionic emission are equally important for the low resistivity of these contacts. Band-gap narrowing and/or image force lowering due to heavy doping also contribute to the resistivity reduction of these contacts. An exciting feature of the present study is the observation of a very low work function intermetallic alloy formed during annealing of an appropriate combination of large work function metals. If the annealing conditions are optimized, the contacts become very robust, thermally stable, and lowly resistive with thermionic emission as the primary mechanism for electron transport. The observation is very promising and has potential to open up avenues for different types of thermionic contacts. The fundamental physics underlying the design principles are discussed. These principles are general enough to be applicable to other III-V nitrides, at the least. (C) 2004 American Institute of Physics.