# 臺灣博碩士論文加值系統

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 本論文以研究於具PN接面的新型態自旋電晶體。此一型態自旋電晶體主要是在Si（100）上結合磁阻元件（巨磁阻或穿隧磁阻）與PN接面所製做而成的自旋閥電晶體或磁穿隧電晶體。自旋閥電晶體於室溫與具有射極偏壓和基極偏壓的共集電路量測中，射極電流於磁矩平行排列時為1mA，於磁矩反平行排列時為0.968mA。相同的狀況下，基極電流變化從29.3mA到333nA。其電流變化率為8600%，交換率（IB/IE）為3×10−2。於低溫（77K）與利用5.12V的射極偏壓與一基極電阻所構成的共集電路量測中，可得集極電流變化率為3400％。集極電流於磁矩排列為平行態時為95.5uA，電流轉換率為2.59E−3。於室溫量測時，集極電流輸出變為98.3uA，變化率降至55.3％，轉換率為5.98×E−3。以上的實驗可利用實驗值與電腦計算加以驗證。並且找出一適當的射極偏壓與基極電阻，可以得到最高的集極電流變化率。磁性穿隧電晶體於室溫量測與一具有射極偏壓與基極偏壓的共集電路量測中，可以得到基極電流從1.9nA變化到123nA，其變化率為6300%。於室溫與具有射極偏壓與基極電阻的共集電路量測中可發現，射極偏壓為1.25±025V時，集極電流變化率均大於40%。且於磁矩平行態排列時，輸出電流（集極電流）均大於4uA。除此之外，自旋閥電晶體於室溫且AC頻率從100 Hz到15 MHz阻抗亦被研究。將一自旋閥電晶體視為數個電阻、電容與電感的等效電路。其中阻抗包含的實部部分（R）與虛部部分（X）。於頻率分別為6.5Hz與3.65Hz時，MZ與MX分別趨近於零。實驗發現剛幫頻率小於這兩個值時，MZ與MX對磁場的表現將發生反相的結果。而這些結果將有助於自旋電晶體於高頻應用時的研究。
 This work has focused on the study of two new type silicon-base spin transistors. These two new type spin transistors are combined either pseudo spin-valve or magnetic tunneling junction with a p-n junction to form a spin-valve transistor (SVT) or magnetic tunneling transistor (MTT). For SVT, the emitter current (IE) changed from 1uA to 0.968uA at different magnetically states in the common collector (CC) circuitry with an emitter bias (VE) and a base bias (VB) at room temperature (RT). At the same states the base currents (IB) changed form 29.3 uA to 333 nA which gave a magnetocurrent (MC) of 8600% and a transfer ratio (α) of 3E−2. In CC configuration with a base resistor (RB) and an VE of 5.12 V at 77 K gives a large collector current (IC) of more than 95.5 mA and the change is more than 3400% with a α of 2.59E−3. At RT, these changes go down to 98.3 mA and 55.3%, respectively, and the α rises to 5.98E−3. The MC of the collector in a SVT has been studied with both experiments and computer calculations. For MTT, IB change of roughly 6300% has been observed in the CC configuration with an VE and a VB at RT. In CC configuration with VE and RB at RT, the MC of the collector can be stabilized roughly above 40% at VE = 1.25±025V with α of 2.88% in the CC circuitry. IC can be more than 4 uA at the magnetic parallel state. The magnetoimpedance (MZ) effect of the SVT was investigated at RT in the frequency ranged from 100 Hz to 15 MHz. The SVT can be regarded as a complex combination of resistors, inductors, and capacitors; all these components exhibit magnetic hysteresis. It is due to the frequency dependent behavior that R does not reach a minimum at the resonant frequency (fr). The frequency dependences of MZ and MX ratios cross zero at fx = 6.5 MHz and at fr=3.65 MHz, respectively. The shape of magnetoreactance loop is reversed to the magnetoresistance loop. The MZ loop also reverses shape and sign after crossing fx.
 Contents i中文摘要 iiAbstract iiiList of Figures ivList of Tables ixChapter 1 Introduction 1Chapter 2 Review of Magnetoresistance effects and the spin-valve transistors 6 2-1 Magnetoresistance effects 6 2-2 M. Johnson all-metal spin transistor 16 2-3 Spin-valve transistor 20 2-4 Magnetic tunneling transistor 24Chapter 3 Instruments and the fabrication processes 31 3-1 Deposition setup 31 3-2 ultraviolet light assisted oxidation equipment 32 3-3 Electron beam lithography system 34 3-4 The fabrication processes of the spin transistors 36Chapter 4 Results and discussions 43 4-1 Pseudo spin-valve transistor 43 4-2 Theory simulation 60 4-3 Magnetic tunneling transistor 66 4-4 Impedance Behavior of Spin Valve Transistor 76Chapter 5 Conclusion 84Bibliography 88