利用有機金屬化學氣相沉積法成長氮化鎵薄膜於電子束蒸鍍金屬層

Abstract

本論文主要為利用有機金屬化學氣相沉積系統磊晶成長氮化鎵薄膜於電子束蒸鍍金屬層，並探討氮化鎵成長機制，以兩階段成長方式磊晶成長表面形貌平整的氮化鎵薄膜於優化厚度電子束蒸鍍金屬層在藍寶石基板，使用光激發螢光光譜量測系統和X-ray繞射儀量測氮化鎵薄膜品質，計算氮化鎵島狀物成長於電子束蒸鍍金屬層在成長初期島狀物的側向成長速度和垂直成長速度的比率，並分析氮化鎵成核於不同厚度電子束蒸鍍金屬層的氮化鎵島狀物成核密度和大小，以及使用X射線光電子能譜儀量測經過氮化製程後的鈦金屬層及鉻金屬層鍵節能，藉此了解鈦金屬層和鉻金屬層兩者所扮演的角色，最後綜合各項分析結果比較兩者的差異之處。 由光激發螢光光譜量測結果顯示，氮化鎵薄膜成長於電子束蒸鍍鈦金屬層和鉻金屬層在藍寶石基板為一個完整的氮化鎵薄膜；而氮化鎵(102)面的半高寬量測分析結果顯示，氮化鎵薄膜成長於電子束蒸鍍鈦金屬層和鉻金屬層在藍寶石基板，其氮化鎵(102)面半高寬數值分別為946.9 arcsecs與773.3 arcsecs，其氮化鎵薄膜品質比起成長於傳統氮化鋁緩衝層的氮化鎵薄膜品質來的差。 藉由分析氮化鎵成核密度和島狀物大小於不同厚度電子束蒸鍍金屬層結果可知，鈦金屬層提供了氮化鎵成核於藍寶石基板的成長窗口，鈦金屬層當遮罩層，鉻金屬層作為氮化鎵和藍寶石基板之間的緩衝層。經由計算在成長初期氮化鎵島狀物的大小知道，成長於電子束蒸鍍鈦金屬層在藍寶石基板的氮化鎵島狀物側向成長速度為垂直成長速度的2.31倍，而成長於電子束蒸鍍鉻金屬層在藍寶石基板為1.51倍。而氮化鎵薄膜成長於電子束蒸鍍鉻金屬層以3D成長為主宰的關係,其容易得到一個表面形貌平整的氮化鎵薄膜於電子束蒸鍍鉻金屬。 因此本論文成功的利用有機金屬化學氣相沉積法成長氮化鎵薄膜於電子束蒸鍍金屬層，並且對氮化鎵的成長特性進行了一系列的分析，進而確切了解氮化鎵薄膜成長於電子束蒸鍍鈦金屬層和鉻金屬層的成長機制。

This study mainly investigated the growth of GaN films on electron-beam evaporated metal layers using an organic metal chemical vapor deposition system and further explored the growth mechanism of GaN. The smooth surface morphology of the grown GaN film on optimizing the thickness of the electron-beam evaporated metal layer on sapphire substrate was identified using a two-step growth process. The quality of the GaN film was measured by photoluminescence spectroscopy and X-ray diffraction analyses. The lateral and vertical growth rate ratios of the island-grown GaN on electron-beam evaporated metal layers were calculated in the initial growth stage. Analysis of island density and size of GaN nucleate on electron-beam evaporated metal layers with different thicknesses was carried out by X-ray photoelectron spectroscopy (XPS). XPS measured the binding energies of the titanium and chromium metals after the nitridation process to determine the roles of the titanium and chromium metal layers. Finally, analysis results were integrated and compared with two other studies in the same Department. Results of the photoluminescence measurements show that GaN films grown on the electron-beam evaporated titanium and chromium metal layers on a sapphire substrate are complete GaN films. The FWHM of GaN (102) rocking curve show results of the GaN thin film grown on electron-beam evaporated titanium and chromium metal layers on a sapphire substrate; the FWHM of the GaN (102) rocking curve were 946.9 and 773.3 arcsecs for the titanium and chromium metal layers, respectively. Result shows poor GaN film quality that is typical for GaN films grown on an AlN buffer layer. Results of analyzing the GaN island density and size on different thicknesses of electron-beam evaporated metal layers show that the titanium metal layer is the mask layer and provides a growth window for GaN grown on the sapphire substrate. On the other hand, the chromium metal layer is the buffer layer between the GaN film and sapphire substrate. Calculating the island size of GaN in the early known growth, the lateral and vertical growth rate ratios of the GaN island grown on titanium and chromium metal layers were 2.31 and 1.51, respectively. The dominant GaN films grown on electron-beam evaporated chromium metal layer were 3D growths. As such, it is easy to obtain a flat surface morphology of GaN films on the electron-beam evaporated chromium metal. Therefore, this paper has successfully grown GaN films on the electron-beam evaporated metal layer using an organic metal chemical vapor deposition system. A series of analyses on the growth characteristics of the grown GaN determine its growth mechanism on electron-beam evaporated titanium and chromium metal layers.