砷化鎵與磷化銦遠紅外光譜與聲子能態密度之研究

Abstract

我們使用傅氏紅外光譜儀量測了砷化鎵與磷化銦兩個代表性的三五族半導體材料的遠紅外波段頻譜，並分析於頻譜中剩餘射線頻段以外，特徵譜線的產生機制。我們使用了十一個參數的剛性離子模型計算聲子色散關係，並使用特殊k點方法得到雙聲子的能態密度頻譜。藉由比對特徵譜線與能態密度頻譜的強度、位置以及形狀，將這些特徵譜線的來源歸因於特定的雙聲子組合以及臨界點。我們在不可約布里淵區中分析臨界點的所在位置，發現臨界點的分布不僅限於對稱性好的對稱點與對稱線上，也存在於不可約布里淵區中的三個對稱面上。

We measured and analyzed the far infrared spectra of two typical III-V semiconductors, GaAs and InP. The measurement was performed by an FTIR at room temperature. Observed features other than the Reststrahlen-band were assigned critical points associated with specific two-phonon combinations, according to the strength, position, and shape of two-phonon densities of states which were calculated by the 11-parameter rigid-ion model and the special-k point method. The critical points are related to van Hove singularities of the density-of-states spectra. We located the critical points in an irreducible wedge of the first Brillouin zone and found that the critical points responsible for most prominent features are located not only at high-symmetry points and lines but also on the quadrangular faces of the irreducible wedge.