多銦氮化銦鎵薄膜之電子傳輸特性

Abstract

本論文主要是探討多銦氮化銦鎵薄膜InxGa1-xN (x = 1, 0.98, 0.92, 0.8, 0.7) 的電子傳輸性質。我們測量了大溫度範圍下氮化銦鎵的電子 傳輸特性。我們發現在實驗誤差範圍內，樣品的載子濃度在測量的溫 度範圍內幾乎與溫度無關，這是金屬的行為。此外我們利用van der Pauw 四點量測法計算樣品的電阻率。綜合電阻率與載子濃度的數據 顯示，我們的樣品隨著鎵的成分上升，有一個由金屬到半導體的轉 變。我們也計算了樣品的載子遷移率，載子遷移率在整個量測的溫度 範圍內，隨著鎵成分的升高而降低，這也印證了氮化銦的傳輸特性優 於氮化鎵。由於金屬電阻率在低溫下遵守Bloch T5 定理，對於銦濃 度大於等於92% 的樣品，我們檢查了它們的電阻率與Bloch T5 定 理的符合程度。分析的結果顯示高銦成分的樣品的電阻率非常符合 Bloch T5 定理，從而進一步的支持了高銦濃度的氮化銦鎵薄膜傳輸特 性與金屬十分類似。

This thesis focuses on electron transport properties in InxGa1−xN (x =1, 0.98, 0.92, 0.8, 0.7) thin films. We have performed transport measurements on InxGa1−xN thin films over a wide temperature range. We observed that within experimental error, the carrier densities are temperature independent. Besides, the resistivities, combined with the carrier densities, show a tendency of transition from metal to semiconductor with increasing Ga composition. The calculated mobility shows that for metallic like samples (InxGa1−xN with x ≥0.92), the dominant scattering mechanism is the imperfection scattering over the whole temperature range. We also showed that Bloch T5 curves fit very well the resistivities of samples InxGa1−xN with x =1, 0.98, 0.92, once again supporting that very high In composition InxGa1−xN films can be considered as degenerate electron systems in which the Fermi level is much higher than conduction-band bottom over the whole measurement range.