氮化銦、氮砷化銦及磷化銦鎵鋁薄膜的紅外線光譜研究

Abstract

在我的論文中，我們藉由分析半導體材料的紅外光譜圖，來研究它們的光學特性，而不同濃度參雜的成長在藍寶石基板上的氮化銦薄膜、成長在磷化銦基板上的氮砷化銦 (參雜氮)薄膜及成長在砷化鎵基板上的磷化銦鎵鋁薄膜都是本次實驗的研究樣品。 紅外線光譜學是一種非破壞性的量測方法，可以在不破壞樣品的情況下，利用晶格的震盪特性，取得樣品的資訊。本研究使用傅立葉式紅外光譜儀(FTIR) Bruker IFS 66 v/S，進行一系列的室溫(300K)的遠紅外線反射光譜測量。我們並利用介電方程式分析由實驗得到的遠紅外線反射光譜，藉由光譜的模擬，計算出光學聲子及載子特性。 從氮化銦的紅外光譜中，我們利用擬和的方法，在大約473~478 (cm−1) 找到了一個氮化銦的E1聲子模。從氮砷化銦的紅外光譜中，它的兩個類聲子模頻率都隨著氮含量的增加而增加且載流子濃度與有效質量隨著氮含量的增加而增加，但遷移率是減少的。從磷化銦鎵鋁的紅外光譜中，發現有四個明顯的鋒值，一個來自砷化鎵基底而另外三個磷化銦鎵鋁薄膜，但也發現了第五個鋒值，其原因可能來自於磷化銦鎵鋁形成Cu-Pt結構而導致峰值的分裂。以及磷化銦與磷化鎵之間發生強烈的耦合導致峰值的結合，使得鋒值只剩三個。 這個研究也界定了這些樣品的高頻介電常數、載子濃度、遷移率、有效質量及薄膜厚度。而我們同樣的也可計算出樣品的導電度。研究結果對於這些半導體的資訊建立有很好的貢獻，也可做為這些材料在應用上的參考依據。

In this thesis, we study the optical properties of semiconductor materials, especially on infrared reflectance spectra, the InN films grown on sapphire substrates, different compositions of series of InAs1-xNx films grown on InP substrates and In0.5(Ga1-xAlx)0.5P films grown on GaAs substrates were used in this study. Infrared spectroscopy is a non-destructive measurement which can get the information from the lattice vibrations of the samples without doing any damage. Fourier transform infrared (FTIR) Bruker IFS 66 V/S were employed to do a series measurements. A dielectric response model was used to determine the optical and transport properties of the semiconductors. From infrared spectra of InN/sapphire, we found the E1 (TO) phonon mode frequencies were obtained at 473~478 cm−1 by dielectric response function fitting. From infrared spectra of InAs1-xNx/InP, the InAs-like TO phonon mode increases with the increase of N composition x and the InN-like TO phonon mode also increases with the increase of N composition x. With increasing x, the effective mass and carrier concentration increase greatly but mobility decrease greatly. From infrared spectra of In0.5(Ga1-xAlx)0.5P/GaAs, there are apparently four main peaks. And we also could define the four TO frequency peak from low frequency to higher frequency are the GaAs phonon mode, InP-, GaP- and AlP-like phonon mode that similar with reference. However, there is a fifth phonon mode that is the Cu-pt type ordered characteristics affect the TO-phonon peak split into two TO mode. And the InP and GaP mode combine into one mode that the effects are made possible by the strong coupling between the Ga-P and In-P vibrations. In my works, we also have analyzed the high-frequency dielectric constant, carrier concentration, mobility and effective mass and the thickness of the films of these materials. Conductivity had been calculated, too. This study established a data base of these materials and provides a reference for their applications.