梁啟德臺灣大學：物理研究所陳上佳Chen, Shang-ChiaShang-ChiaChen2007-11-262018-06-282007-11-262018-06-282005http://ntur.lib.ntu.edu.tw//handle/246246/54548霍爾效應與SdH震盪是研究半導體電性常用的兩種測量，本論文包括兩部分，分別與這兩種測量有關： 1.氮化銦薄膜的電子傳輸特性： 我們研究大溫度範圍內，氮化銦薄膜的電子傳輸特性。我們發現在誤差範圍內，氮化銦薄膜的載子濃度隨溫度幾乎不變，此結果與金屬特性相似。此外，因為低溫下電阻率只比室溫電阻率約小百分之十，我們可知主要的散射來自於雜質，故若要提昇氮化銦薄膜的傳輸性，必須減少長膜過程中生成的缺陷。另外我們對晶格散射造成遷徙率隨溫度變化的部份做分析，發現在120K-240 K範圍內，呈現溫度五次方關係，亦與金屬特性相似。我們的結論是雖然氮化銦是半導體材料，電子傳輸特性卻類似金屬。 2. 微波調製技術下，砷化鎵／砷化鋁鎵異質結構的電子傳輸特性： 我們利用微波調製技術來提高系統中SdH震盪訊號的靈敏度。但在數據分析上，我們發現必須知道微波照射下的電子溫度，故我們進行校正電子溫度的實驗。經由比較改變溫度的SdH震盪圖形和照射不同功率連續微波下的SdH震盪圖形，我們發現電子上升的溫度非常小，小於0.3 K。同時我們也觀察了微波調製下的自旋分裂現象，發現不對稱圖形，但我們尚未找到合理的解釋。Hall effect and Shubnikov-de Haas (SdH) effect measurements are two most frequently used tools for characterizing the electronic transport properties in a semiconductor. This dissertation consists of the following two parts, regarding these two techeniques respectively. 1.Electron transport in InN films We have preformed the electric transport measurements on InN films overa wide temperature range. Our results show that, within the experimental error, the carrier density are temperature-independent, similar to that in a metal. Such results indicate that we can consider our InN films as degenerate electron systems in which the Fermi level is much higher than the conduction band over the whole measurement range. Moreover, our results suggest that over a wide temperature range the dominant scattering mechanism is residue imperfection scattering since ρRT is only 10% more than ρ4k. That tells us in InN films it is the residue impurity scattering limits the electronic transport. So in order to obtain higher-mobility InN system, one needs to substantially reduce the number of background impurities and defects during the growth. Our data demonstrate that electron transport in InN is metallic-like, which is further supported by the observation that temperature dependence of the acoustic-phonon mobility shows a T-5 dependence. 2.Microwave-modulated transport in a GaAs/AlGaAs electron system : Measurements of microwave-modulated SdH-like oscillation were carried out in a GaAs/AlGaAs heterostructure. The microwave-modulation technique is used to enhance the visibility of the oscillatory pattern while keeping the carrier density constant, and I performed some further measurements in order to figure out the exact electron temperature when the sample is under microwave illumination. By comparing the SdH oscillations under continuous microwave with different power and SdH oscillations at different temperature, our results show that the electron temperature increase is very small, less than 0.3 K. Besides, the spin-splitting phenomenon under chopped microwave is also observed, and the oscillatory pattern is asymmetric. At present, we have not found a plausible explanation of it.Preface.................................................1 Chapter 1 Introduction..................................2 1-1 Introduction........................................2 1-1-1 Indium Nitride....................................2 1-1-2 Some unique properties of InN.....................2 1-2 Basic concept ......................................3 1-2-1 Classical Hall effect.............................3 1-2-2 Van der Pauw measurement..........................4 1-2-3 Classical Drude model.............................5 1-3 Theoretical background..............................8 Chapter 2 Electron transport in InN films........................10 2-1 Sample structure...................................10 2-2 Experimental procedure.............................11 2-3 Results and discussions............................12 2-3-1 Temperature dependence of resistivity and carrier density................................................12 2-3-2 Temperature dependence of Mobility...............14 2-4 Summary............................................17 Chapter 3 Introduction to two-dimensional electron system .......19 3-1 Introduction.......................................19 3-2 Basic concept......................................20 3-2-1 GaAs two-dimnsional electron gas.................20 3-2-2 Landau level and Shubnikov-de Hassoscillations...21 3-2-1 The spin-splitting phenomenon....................24 Chapter 4 Microwave-modulated transport in a GaAs/AlGaAs electron system ................................................27 4-1 The microwave-modulation technique.................27 4-2 Experiment.........................................33 4-3 Results and discussion.............................36 4-3-1 Calibration of electron temperature..............36 4-3-2 Dependence of modulated SdH oscillations on microwave power........................................39 4-4 Summary............................................41 Chapter 5 Conclusions............................................42523035 bytesapplication/pdfen-US氮化銦砷化鎵微波調製InNHall effectGaAs/AlGaAsMicrowave-modulatedthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/54548/1/ntu-94-R92222032-1.pdf