Capacitance-Voltage Characteristics of Al2O3/AlGaN/GaN Structures and State Density Distribution at Al2O3/AlGaN Interface
Capacitance-Voltage Characteristics of Al2O3/AlGaN/GaN Structures and State Density Distribution at Al2O3/AlGaN Interface
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DOI：
10.1143/jjap.50.021001
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发表时间：
2011-02-01
影响因子：
1.5
通讯作者：
Hashizume, Tamotsu
中科院分区：
文献类型：
--
作者：
Mizue, Chihoko;Hori, Yujin;Hashizume, Tamotsu
通过原子层沉积 (ALD) 制备的 Al2O3/Al0.25Ga0.75N/GaN 结构的电势调制和界面态通过电容-电压 (C-V) 测量进行表征。我们在正向和反向偏压区域观察到具有两个电容阶跃的奇特 C-V 特性，对应于 Al2O3/AlGaN 和 AlGaN/GaN 界面处的电子积累或耗尽行为。从实验和计算的C-V特性发现，AlGaN导带边缘附近界面态的充放电主要引起正向偏压时C-V曲线的伸展和滞后。另一方面，中间能隙附近或更深处的界面态很可能充当固定电荷。根据正向偏压区域中与偏压相关的磁滞电压和反向偏压下的光致电压偏移，我们首次估计了 Al2O3/AlGaN 界面处的界面态密度分布。目前的ALD-Al2O3/AlGaN/GaN结构表现出相对较高的界面态密度，最小密度为1 x 10(12) cm(-2) eV(-1)或更高。 (C) 2011 日本应用物理学会
The potential modulation and interface states of Al2O3/Al0.25Ga0.75N/GaN structures prepared by atomic layer deposition (ALD) were characterized by capacitance-voltage (C-V) measurements. We observed the peculiar C-V characteristics with two capacitance steps in forward and reverse bias regions, corresponding to the electron accumulation or depletion behavior at the Al2O3/AlGaN and AlGaN/GaN interfaces. From the experimental and calculated C-V characteristics, it was found that the charging and discharging of interface states near the AlGaN conduction-band edge mainly caused the stretch-out and hysteresis of the C-V curve at the forward bias. On the other hand, it is likely that the interface states near the midgap or deeper in energies act as fixed charges. From the bias-dependent hysteresis voltage in the forward bias region and the photo-induced voltage shift at the reverse bias, we estimated the interface state density distribution at the Al2O3/AlGaN interface for the first time. The present ALD-Al2O3/AlGaN/GaN structure showed relatively high interface state densities with a minimum density of 1 x 10(12) cm(-2) eV(-1) or higher. (C) 2011 The Japan Society of Applied Physics