Charge neutrality levels, barrier heights, and band offsets at polar AlGaN
Charge neutrality levels, barrier heights, and band offsets at polar AlGaN
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DOI：
10.1063/1.4930026
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发表时间：
2015-09
影响因子：
4
通讯作者：
P. Reddy;I. Bryan;Z. Bryan;J. Tweedie;S. Washiyama;R. Kirste;S. Mita;R. Collazo;Z. Sitar
中科院分区：
文献类型：
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作者：
P. Reddy;I. Bryan;Z. Bryan;J. Tweedie;S. Washiyama;R. Kirste;S. Mita;R. Collazo;Z. Sitar
在这项工作中，费米能级和带的取向在c-平面表面和界面上生长的AlGaN薄膜蓝宝石和原生单晶AlN衬底通过X射线光电子能谱分析。发现电荷中性水平（CNL）对Al组分的依赖性与n型肖特基势垒高度（Φbn）呈线性关系，由于带隙弯曲，表现出总体的二次行为。利用界面诱导能隙态（IFIGS）模型确定AlGaN上肖特基势垒高度的一般理论表达式作为Al组分和金属电负性的函数，并与Ni基肖特基二极管的电流-电压特性（I-V）进行了验证。测量的CNL用于根据IFIG确定AlGaN异质结中的导带和价带偏移，并且发现在具有可比Al和Ga浓度的AlGaN的界面处分别分裂约2/3和1/3的带隙。Φbn结果中的非线性...
In this work, the Fermi level and band alignment at c-plane surfaces and interfaces of AlGaN thin films grown on sapphire and native single crystalline AlN substrates were analyzed via x-ray photoelectron spectroscopy. The dependence of charge neutrality level (CNL) on Al composition is found to be linear with n-type Schottky barrier heights (Φbn) exhibiting an overall quadratic behavior due to bandgap bowing. A general theoretical expression for Schottky barrier height on AlGaN is determined as a function of Al composition and metal electronegativity utilizing the interface induced gap states (IFIGS) model and is corroborated with current-voltage (I-V) characterization on Ni-based Schottky diodes. The measured CNLs were used to determine the conduction and valence band offsets in AlGaN hetero-junctions according to the IFIGS and were found to be split approximately 2/3 and 1/3 of the bandgap, respectively, at interfaces with AlGaN having comparable Al and Ga concentrations. Nonlinearities in Φbn result i...