具漸變摻雜基極之磷化銦鎵/砷化鎵穿透式集極
異質雙載子電晶體之研究

呂專豪* 許渭州**

國立成功大學電機系微電子工程研究所

摘要

在本文中，我們利用低壓有機金屬化學氣相沈積法，成長具有銦組成成份漸變式(Compositionally Graded)摻雜基極且具有穿透式集極之磷化銦鎵/砷化鎵(InGaP/GaAs)系統異質雙載子電晶體。實驗結果顯示偏移電壓(offset voltage) 由130 mV降為25 mV，而膝電壓(knee voltage) 由910 mV降為400 mV，此主因為基-射(B-E)及基-集(B-C)接面之不對稱因加入穿透式集極而改善。溫度變化方面以穿透式集極結構較不明顯，在電流密度20 kA/cm2下室溫從300 K到450 K直流增異變化分別是5%及35%，顯示出優異之熱穩定度特性。高頻特性方面，fT 經由銦組成成份漸變式基極效果可由37 GHz提升至44 GHz，而且fmax也可由40 GHz提升至53 GHz。此改善主因為漸變式基極之內建電場（縮短基極傳輸時間）及較小基極電阻(RB)。

作者*
指導教授**

　Study of InGaP/GaAs Tunnel-Collector HBT with 　　　　　　Compositionally Graded Base

　　　　　　Chuan-Hao Lu* Wei-Chou Hsu**

　　Institute of Microelectronics, Department of 　　　　　　　　　Electrical Engineering　
　　　National Cheng Kung　University,Tainan,
　　　　　　　　　　Taiwan, R.O.C.

　　　　　　　　　Abstract

In this thesis, we fabricated InGaP/GaAs heterojunction bipolar transistors with indium compositionally graded base and tunnel-collector layer by MOCVD system. Experimental results show that the offset voltage reduces from 130 mV to 25 mV, and knee voltage reduces from 910 mV to 400 mV due to the asymmetry of base-emitter (B-E) and base-collector (B-C) junctions is eased by the addition of tunnel-collector layer. Furthermore, tunnel-collector structure also has less temperature sensitivity due to the variations in current gain is below 5% compared to 35% of SHBT at temperature from 300 K to 450 K at current density of 20 kA/cm2. This reveals excellent thermal stability characteristic. In RF performance, the indium compositionally graded base makes fT rise from 37 GHz to 44 GHz and fmax increase from 40 GHz to 53 GHz. This improvement is mainly resulted from the build-in electrical field (shorter base-transient time) and smaller base resistance (RB).

* Author
** Advisor
　

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