〈331〉晶向ZnTe单晶的太赫兹辐射-探测性能理论研究

根据光整流效应辐射太赫兹理论,计算了〈331〉晶向ZnTe单晶的太赫兹辐射性能.通过与〈110〉、〈111〉晶向对比,当晶体方位角为0°或180°时,利用〈331〉晶向ZnTe单晶辐射太赫兹信号可以与〈111〉晶向相当,强于〈110〉晶向.利用电光取样原理,计算了〈331〉晶向ZnTe单晶的太赫兹探测性能,通过理论计算为〈331〉晶向ZnTe晶体有效辐射太赫兹波提供理论依据.     

《331》晶向ZnTe单晶的太赫兹辐射及探测

通过Te熔剂方法生长出〈331〉晶向的ZnTe体单晶,利用X射线衍射和红外透射显微技术对材料进行了测试.在钛-宝石激光器的泵浦下,利用〈331〉晶向的ZnTe晶体辐射-探测到太赫兹波,激发频谱可达5 THz左右.〈331〉晶向的ZnTe晶体表现出良好的太赫兹辐射性能.     

〈331〉晶向ZnTe单晶的太赫兹辐射-探测性能理论研究

根据光整流效应辐射太赫兹理论,计算了〈331〉晶向ZnTe单晶的太赫兹辐射性能.通过与〈110〉、〈111〉晶向对比,当晶体方位角为0°或180°时,利用〈331〉晶向ZnTe单晶辐射太赫兹信号可以与〈111〉晶向相当,强于〈110〉晶向.利用电光取样原理,计算了〈331〉晶向ZnTe单晶的太赫兹探测性能,通过理论计算为〈331〉晶向ZnTe 晶体有效辐射太赫兹波提供理论依据.     

Positive and Negative Pulse Etching Method of Porous Silicon Fabrication

We present a new method in which both positive and negative pulses are used to etch silicon for fabrication of porous silicon （PS） monolayer. The optical thickness and morphology of PS monolayer fabricated with different negative pulse voltages are investigated by means of reflectance spectra, scanning electron microscopy and photoluminescence spectra. It is found that with this method the PS monolayer is thicker and more uniform. The micropores also appear to be more regular than those made by common positive pulse etching. This phenomenon is attributed to the vertical etching effect of the PS monolayer being strengthened while lateral etching process is restrained. The explanation we propose is that negative pulse can help the hydrogen cations （H^＋） in the electrolyte move into the micropores of PS monolayer. These H^＋ ions combine with the Si atoms on the wall of new-formed micropores, leading to formation of Si-H bonds. The formation of Silt bonds results in a hole depletion layer near the micropore wall surface, which decreases hole density on the surface, preventing the micropore wall from being eroded laterally by F^- anions. Therefore during the positive pulse period the etching reaction occurs exclusively only at the bottom of the micropores where lots of holes are provided by the anode.