梁啟德臺灣大學：物理研究所林士凱Lin, Shih-KaiShih-KaiLin2007-11-262018-06-282007-11-262018-06-282005http://ntur.lib.ntu.edu.tw//handle/246246/54465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.1 Introduction 1 2 Theoretical background 4 2.1 Classical Hall effect . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Van der Pauwmethod . . . . . . . . . . . . . . . . . . . . . . 6 2.3 Electrical transport properties . . . . . . . . . . . . . . . . . . 10 2.3.1 Ohm’s law and electrical conductivity . . . . . . . . . . 10 2.3.2 Relaxation time approximation . . . . . . . . . . . . . 12 2.3.3 The temperature-dependent electron resistivity of metals 14 3 Sample fabrication and Hall measurements 20 3.1 Sample fabrication . . . . . . . . . . . . . . . . . . . . . . . . 20 3.1.1 Metal-organic vapor phase epitaxy . . . . . . . . . . . 20 3.1.2 Sample structure . . . . . . . . . . . . . . . . . . . . . 21 3.2 Hall measurements . . . . . . . . . . . . . . . . . . . . . . . . 23 3.2.1 Experimental setup . . . . . . . . . . . . . . . . . . . . 23 3.2.2 Ohmic contacts . . . . . . . . . . . . . . . . . . . . . . 23 3.2.3 Elimination of background voltage . . . . . . . . . . . 25 4 Electrical properties of In-rich InxGa1−xN films 27 4.1 Deviation of the Rxy fromzero at zero magnetic field . . . . . 27 4.2 Temperature dependence of carrier density, resistivity and mobility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 4.3 Curve fitting of Bloch T5 law . . . . . . . . . . . . . . . . . . 38 5 Conclusions 42 Bibliography 441710478 bytesapplication/pdfen-US氮化銦鎵InGaNthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/54465/1/ntu-94-R92222049-1.pdf