Electrochemical characteristics of n-type GaN in oxalic acid solution under the pre-breakdown condition
Electrochemical characteristics of n-type GaN in oxalic acid solution under the pre-breakdown condition
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n型GaN在草酸溶液中预击穿条件下的电化学特性
DOI：
10.1016/j.jallcom.2015.08.115
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发表时间：
2015-12-15
影响因子：
6.2
通讯作者：
Liu, Xiangdong
中科院分区：
文献类型：
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作者：
Cao, Dezhong;Xiao, Hongdi;Liu, Xiangdong
采用循环伏安法、计时安培法和电化学阻抗法对n型氮化镓在草酸溶液中预击穿条件下的蚀刻过程进行了评价。利用多变量曲线分辨率替代最小二乘模型分析了时间电流图，表明法拉第电流随施加偏置的增加而增加，充电电流与GaN薄膜的有源面积有关。为了研究坑形成过程中的电化学特性，我们将GaN工作电极/电解质界面上的参数变化（如电容和电阻）与电解变量的参数映射联系起来。在相同的蚀刻条件下，观察到三个显著的趋势：(1)电容随施加偏置的增加而减小，(2)电容随草酸浓度的增加而减小，(3)电容随掺杂浓度的增加而增大，电阻随掺杂浓度的增加而减小。在不同的酸浓度和施加偏置下，氮化镓表面的氧化物堆积导致了电阻的增加。但该结论不适用于不同的掺杂浓度。(C) 2015 Elsevier B.V.版权所有
Cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy are used to evaluate the etching of n-type GaN in oxalic acid solution under the pre-breakdown condition which leads to the pit formation on the GaN surface. The chronoamperograms are analyzed using a multivariate curve resolution alternative least square model, indicating that faradaic current increases with the applied bias rising, and that charging current depends on the active area of GaN thin films. To study the electrochemical characteristics during the pit formation, we correlated the changes of parameters (e.g. capacitance and resistance) at the GaN working electrode/electrolyte interface with a parametric mapping of electrolysis variables. Under the same etching condition, three notable trends were observed (i) the capacitance decrease and the resistance increase with the applied bias rising, (ii) the decrease of capacitance and resistance as the oxalic acid concentration increases, and (iii) the capacitance increase and the resistance decrease with the rise of doping concentration. The increase of resistance could be ascribed to the oxide accumulation on the GaN surface under different acid concentrations and applied biases, respectively. However, the conclusion cannot be applied in different doping concentrations. (C) 2015 Elsevier B.V. All rights reserved.