Izumi Ryo, Miyazaki Masato, Li Yan Jun, Sugawara Yasuhiro
Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Beilstein J Nanotechnol. 2023 Jan 31;14:175-189. doi: 10.3762/bjnano.14.18. eCollection 2023.
The recently proposed high-low Kelvin probe force microscopy (KPFM) enables evaluation of the effects of semiconductor interface states with high spatial resolution using high and low AC bias frequencies compared with the cutoff frequency of the carrier transfer between the interface and bulk states. Information on the energy spectrum of the interface state density is important for actual semiconductor device evaluation, and there is a need to develop a method for obtaining such physical quantities. Here, we propose high-low Kelvin probe force spectroscopy (high-low KPFS), an electrostatic force spectroscopy method using high- and low-frequency AC bias voltages to measure the interface state density inside semiconductors. We derive an analytical expression for the electrostatic forces between a tip and a semiconductor sample in the accumulation, depletion, and inversion regions, taking into account the charge transfer between the bulk and interface states in semiconductors. We show that the analysis of electrostatic forces in the depletion region at high- and low-frequency AC bias voltages provides information about the interface state density in the semiconductor bandgap. As a preliminary experiment, high-low KPFS measurements were performed on ion-implanted silicon surfaces to confirm the dependence of the electrostatic force on the frequency of the AC bias voltage and obtain the interface state density.
最近提出的高低温开尔文探针力显微镜（KPFM），与界面态和体相态之间载流子转移的截止频率相比，利用高、低交流偏置频率，能够以高空间分辨率评估半导体界面态的影响。界面态密度的能谱信息对于实际半导体器件评估很重要，因此需要开发一种获取此类物理量的方法。在此，我们提出高低温开尔文探针力谱（high-low KPFS），这是一种利用高频和低频交流偏置电压来测量半导体内部界面态密度的静电力谱方法。我们推导了在积累、耗尽和反型区域中，考虑半导体体相态和界面态之间电荷转移时，探针与半导体样品之间静电力的解析表达式。我们表明，在高频和低频交流偏置电压下对耗尽区域静电力的分析，可提供有关半导体带隙中界面态密度的信息。作为初步实验，对离子注入硅表面进行了高低温KPFS测量，以确认静电力对交流偏置电压频率的依赖性，并获得界面态密度。
