Al1-xInxP薄膜拉曼光譜及其高壓效應之研究

Abstract

本論文中，我們利用微拉曼光譜 (Micro-Raman spectroscopy) 研究磷化銦鋁 (Al1-xInxP) 三元化合物薄膜的縱支聲子 (LO phonon) 及橫支聲子 (TO phonon) 振動行為。從實驗結果，我們發現磷化銦鋁 (Al1-xInxP) 三元化合物薄膜是一種 two-mode 系統，因而我們也引用了簡單的 MREI 模型以了解這種振動模式。比較前人的結論，我們發現他們提出的判定條件仍需作適當修改。 我們並利用鑽石高壓砧 (diamond anvil cell, DAC) 的技術產生高壓至20GPa，探討高靜水壓 (high hydrostatic pressure) 效應對其造成之影響。目前我們未曾看到相關的報導。在高壓下，磷化銦鋁 (Al1-xInxP) 三元化合物薄膜所有的振動模均表現出藍位移現象 (blue shift)，並且都顯示出 two-mode 的振動方式。而在回壓的過程中，我們發現這些聲子振動的拉曼譜線並不會回復到原來未加壓的譜線情況。

Microscopic Raman scattering spectroscopy was used to measure the frequencies of longitudinal optical (LO) and transverse optical (TO) phonons in Al1-xInxP thin films for the fractions x＝0.48, 0.50, and 0.52 at ambient pressure and room temperature. It was observed that Al1-xInxP thin films do exhibit two-mode behaviors. Based on the modified random element isodisplacement (MREI) model, the calculated result also manifest that the Al1-xInxP thin films are two-mode systems. In addition, all the variation of the Raman shifts of LO and TO phonons in Al1-xInxP are plotted with respective to the concentration fraction x. We also study the high hydrostatic pressure effects on the Al1-xInxP systems. Pressure is added on to the Al0.52In0.48P, Al0.5In0.5P, and Al0.48In0.52P thin films up to 20GPa. The diamond anvil cell (DAC) was employed to produce high pressure. It was found that the Al1-xInxP thin films exhibit two-mode behaviors and all Raman modes shift to higher frequencies when the pressure is increased up to 15GP.