%A Zhi-Fu Zhu, He-Qiu Zhang, Hong-Wei Liang, Xin-Cun Peng, Ji-Jun Zou, Bin Tang, Guo-Tong Du %T Characterization of Interface State Density of Ni/p-GaN Structures by Capacitance/Conductance-Voltage-Frequency Measurements %0 Journal Article %D 2017 %J Chin. Phys. Lett. %R 10.1088/0256-307X/34/9/097301 %P 097301%V 34 %N 9 %U {https://cpl.iphy.ac.cn/CN/abstract/article_70933.shtml} %8 2017-08-08 %X For the frequency range of 1 kHz–10 MHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage ($C$–$V$) and conductance-frequency-voltage ($G$–$f$–$V$) measurements at room temperature. To obtain the real capacitance and interface state density of the Ni/p-GaN structures, the effects of the series resistance ($R_{\rm s}$) on high-frequency (5 MHz) capacitance values measured at a reverse and a forward bias are investigated. The mean interface state densities obtained from the $C_{\rm HF}$–$C_{\rm LF}$ capacitance and the conductance method are $2\times10^{12}$ eV$^{-1}$cm$^{-2}$ and $0.94\times10^{12}$ eV$^{-1}$cm$^{-2}$, respectively. Furthermore, the interface state density derived from the conductance method is higher than that reported from the Ni/n-GaN in the literature, which is ascribed to a poor crystal quality and to a large defect density of the Mg-doped p-GaN.