臺灣博碩士論文加值系統

　　在本文中，我們將研製具有陡坡和漸變式侷限層的功能型砷化鋁鎵/砷化銦鎵/砷化鎵異質結構射極及異質結構基極雙極性電晶體。由於在射基接面插入砷化銦鎵量子井，使價電帶的不連續度可予增加，因此增加注入效率，兩者的電流增益分別為280及120。另外，適當的設計射極砷化鎵的長度可以消除位障尖峰，所以可以得到100mV之低補偏電壓。透過理論分析，我們可以了解對於不同的射基極電壓，異質結構射極異質結構基極式電晶體之操作特性。
　　此外，在反向操作下我們可發現一個有趣的多重負微分電阻的現象，這是由於累增崩潰和連續的二次位障降低效應所導致電子同時在砷化鋁鎵/砷化鎵界面和砷化銦鎵量子井中產生堆積效應。
　　異質結構射極及異質結構基極式雙極性電晶體由於具有傑出的電晶體特性和多重負微分電阻之現象，可以適用於放大器及多值邏輯電路之應用。

　　In this thesis, the functional AlGaAs/InGaAs/GaAs heterostructure-emitter and heterostructure-base bipolar transistors (HEHBT's) with an abrupt or a graded confinement layer are fabricated and demonstrated. Due to the insertion of InGaAs quantum well at E-B junction, the discontinuity of valence band can be enchanced and the injection efficiency can be increased. The current gain of 280 and 120 are obtained, respectively. The optimum design of the n-GaAs emitter can eliminate the potential spike and get the low offset voltage of 100 mV. From the theoretical analysis, we know that the transistor operation of HEHBT is a function of emitter-base voltage.
　　In addition, an interesting S-shaped multiple negative differential resistance (NMDR) phenomena are observed under the inverted operation mode. This is may be attributed to an avalanche multiplication and sequential two-stage barrier lowering effect resulting from electron accumulation at AlGaAs/GaAS heterointerface and InGaAs quantum well, respectively.
　　Due to the excellent transistor characteristic and MNDR phenomenon, the HEHBT's are suitable for amplification and multiple-valued logic applications.