Ultralow-Contact-Resistance Au-Free Ohmic Contacts With Low Annealing Temperature on AlGaN/GaN Heterostructures
Ultralow-Contact-Resistance Au-Free Ohmic Contacts With Low Annealing Temperature on AlGaN/GaN Heterostructures
复制标题
AlGaN/GaN 异质结构上具有低退火温度的超低接触电阻无金欧姆接触
DOI：
10.1109/led.2018.2822659
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发表时间：
2018-06-01
影响因子：
4.9
通讯作者：
Liu, Xinyu
中科院分区：
文献类型：
--
作者：
Zhang, Jinhan;Kang, Xuanwu;Liu, Xinyu
本文报道了AlGaN/GaN异质结无Au Ti/Al/Ti/TiN接触的电学和微结构特性。获得了超低的无金欧姆接触，接触电阻和接触电阻率分别低<inline-formula><tex-math notation="LaTeX">至0. 21 Ω cm</tex-math></inline-formula>和<inline-formula><tex-math notation="LaTeX">1. 16 × 10 - 6 Ω cm</tex-math></inline-formula>。通过AlGaN势垒的预欧姆凹陷和底部Ti层厚度的优化，欧姆合金温度降低至550 °C。我们发现，欧姆金属和AlGaN表面之间的AlN的界面层的形成是至关重要的实现低接触电阻与降低低退火温度的组合的电气<inline-formula><tex-math notation="LaTeX">${I}$</tex-math></inline-formula>-<inline-formula><tex-math notation="LaTeX">${V}$</tex-math></inline-formula>特性和高分辨率透射电子显微镜分析。此外，我们提出了一个假设，底部Ti层起着催化作用的Al-N反应与优化的厚度。
We report on the electrical and microstructural characterization of Au-free Ti/Al/Ti/TiN contacts for AlGaN/GaN heterostructures. Ultra-low Au-free ohmic contact has been obtained with contact resistance and specific contact resistivity as low as <inline-formula> <tex-math notation="LaTeX">$0.21~\Omega \cdot \text{mm}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">${1.16}\times {10}^{-6} \Omega \cdot \,\,\text{cm}^{2}$ </tex-math></inline-formula>, respectively. The ohmic alloy temperature is reduced as low as 550 °C by pre-ohmic recess of the AlGaN barrier and optimization of the thickness of bottom Ti layer. We found that interfacial layer formation of AlN between the ohmic metal and AlGaN surface is crucial to realize a low contact resistance with reduced low annealing temperature by a combination of electrical <inline-formula> <tex-math notation="LaTeX">${I}$ </tex-math></inline-formula>–<inline-formula> <tex-math notation="LaTeX">${V}$ </tex-math></inline-formula> characterization and high-resolution transmission electron microscopy analysis. Furthermore, we suggest a hypothesis that the bottom Ti layer plays a catalytic role for the Al–N reaction with optimized thickness.