Research in the electronic structure of MnSi/Si interface by soft X-ray emission spectroscopy and inverse resonant photoelectron spectroscopy

近些年来，电子器件在界面领域取得了新的进展，如MNSI/Si层。为了研究MnSi/Si界面的电学性质，我们注意到了软X射线发射光谱和共振反光电子能谱。首先，我们测量了Si单晶的Si-K_β发射光谱。K_β发射谱是由Si3p价带到Si2p核空穴的跃迁引起的。测量采用电子激发法，改变样品表面的X射线起始角(θ_t)。当θ_t=2°时，SiK_β谱代表了体硅的Si3p价带结构。另一方面，在θ_t=0.5时，对应于X射线的全反射角θ_c(临界角)，Si-K_β谱显示了表面氧化硅的电子结构，即SiO_2。当θ_t介于上述角度之间时，在θ_t=1°和1.5°之间，K_β谱显示了SiO_2/Si界面的电子结构，价带Si3p峰系统地向低能方向移动。这种峰位移可以用半导体异质结的能带偏移模型来解释。接下来，我们通过改变起飞角度β_t，观察到了MnSi/Si系统的Si-K_α谱和Mn-K_θ谱。

Recent development of electronic devices has been made in the field of interface such as MnSi/Si layer. In order to study the electronic properties of MnSi/Si interface, we have noticed the soft X-ray emission spectroscopy and the resonant inverse photoelectron spectroscopy.At first, we have measured the Si-K_β emission spectra of Si single crystal. The K_β emission spectrum is induced by the Si 3p valence band to the Si 2p core hole transition. Measurements were carried out by electron excitation method and by changing the X-ray take-off angle (θ_t) from sample surface. When at θ_t = 2 °, SiK_β spectrum represents the Si 3p valence band structure of bulk Si. On the other hand, at θ_t = 0.5 °, which corresponds to the total reflection angle θ_c (critical angle) of X-rays, the Si-K_β spectrum shows the electronic structure of surface oxidized Si, i.e. SiO_2. Where θ_t is between above angles, at θ_t = 1 ° and, 1.5 °, the K_β spectra show the electronic structures of SiO_2/Si interface and the valence band Si3p peak shifts systematically to the lower energy. This peak shift may be understood by the band offset model of semiconductor heterojunction.Next, we observed the Si-K_β spectra and the Mn L_α spectra from MnSi/Si system by changing the take-off angel θ_t.