Department of Physics, Sri Venkateswara University, Tirupati 517 502, India.
School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center, (SPRC), Chonbuk National University, Jeonju 561-756, Republic of Korea.
J Colloid Interface Sci. 2017 Aug 1;499:180-188. doi: 10.1016/j.jcis.2017.03.105. Epub 2017 Mar 29.
An Au/CuZnSnS (CZTS)/n-GaN heterojunction (HJ) is fabricated with a CZTS interlayer and probed its chemical states, structural, electrical and frequency-dependent characteristics by XPS, TEM, I-V and C-V measurements. XPS and TEM results confirmed that the CZTS films are formed on the n-GaN surface. The band gap of deposited CZTS film is found to be 1.55eV. The electrical properties of HJ correlated with the Au/n-GaN Schottky junction (SJ). The Au/CZTS/n-GaN HJ reveals a good rectification nature with high barrier height (0.82eV) compared to the Au/n-GaN SJ (0.69eV), which suggests the barrier height is influenced by the CZTS interlayer. The barrier height values assessed by I-V, Cheung's and Norde functions are closely matched with one other, thus the methods used here are reliable and valid. The extracted interface state density (N) of Au/CZTS/n-GaN HJ is lower compared to the Au/n-GaN SJ that suggests the CZTS interlayer plays an important role in the reduction of N. Moreover, the capacitance-frequency (C-f) and conductance-frequency (G-f) characteristics of SJ and HJ are measured in the range of 1kHz-1MHz, and found that the capacitance and conductance strappingly dependent on frequency. It is found that the N estimated from C-f and G-f characteristics is lower compared to those estimated from I-V characteristics. Analysis confirmed that Poole-Frenkel emission dominates the reverse leakage current in both SJ and HJ, probably related to the structural defects and trap levels in the CZTS interlayer.
采用 Au/CuZnSnS（CZTS）/n-GaN 异质结（HJ），通过 XPS、TEM、I-V 和 C-V 测量研究其化学状态、结构、电学和频率相关特性。XPS 和 TEM 结果证实 CZTS 薄膜在 n-GaN 表面形成。沉积的 CZTS 薄膜的带隙为 1.55eV。HJ 的电学性能与 Au/n-GaN 肖特基结（SJ）相关。与 Au/n-GaN SJ（0.69eV）相比，Au/CZTS/n-GaN HJ 具有良好的整流特性，具有较高的势垒高度（0.82eV），这表明势垒高度受到 CZTS 中间层的影响。通过 I-V、Cheung 和 Norde 函数评估的势垒高度值彼此非常匹配，因此这里使用的方法是可靠和有效的。与 Au/n-GaN SJ 相比，Au/CZTS/n-GaN HJ 的界面态密度（N）较低，这表明 CZTS 中间层在降低 N 方面起着重要作用。此外，在 1kHz-1MHz 的范围内测量 SJ 和 HJ 的电容-频率（C-f）和电导-频率（G-f）特性，发现电容和电导紧密依赖于频率。从 C-f 和 G-f 特性估计的 N 比从 I-V 特性估计的 N 低。分析证实，Poole-Frenkel 发射主导 SJ 和 HJ 中的反向漏电流，可能与 CZTS 中间层中的结构缺陷和陷阱能级有关。
