碲化錳鋅磊晶層的高壓拉曼散射光譜研究

Abstract

我們利用高壓拉曼散射光譜技術來研究參雜不同錳濃度的碲化錳鋅磊晶層，主要探討樣品的聲子頻率與壓力變化的關係。我們發現在高壓下半導體相變成為金屬會伴隨著縱向光學聲子模消失。我們以線性方程式去擬合閃鋅礦結構的聲子頻率與壓力的關係，得到相關的格留乃森(Grüneisen)參數和離子性，隨壓力增加離子性將會減少造成橫向聲子頻率接近縱向聲子頻率。除此之外，我們發現半導體到金屬相變壓力會隨著錳的濃度增加而減少。

The pressure dependence of the optical phonon modes of cubic Zn1-xMnxTe (0≦x≦0.22) epilayers was investigated by using high-pressure Raman scattering technique. The pressure-induced metallization of zinc-blende (ZB) Zn1-xMnxTe together with the disappearance of the longitudinal optical (LO) phonon is observed. The measured phonon frequencies in the ZB phase region are fitted linearly. The Grüneisen parameters of the LO and transverse optical (TO) phonons are calculated. Additionally, the ionicity of the Zn1-xMnxTe layers is discussed. The frequency of TO phonon approaches the LO phonon as the pressure increases due to the decreasing of ionicity. The critical pressure in GPa of semiconductor-to-metal phase transition is found to decrease with the Mn fraction (x) as a function of211.528.754.5Ptx=−−.