摘要
隨著科技的進步，III-V族半導體之微波元件應用在無線通訊上日漸重要；而異質接面雙極性電晶體（Heterojunction Bipolar Transistor，以下簡稱HBT）擁有高功率、線性度佳、用電量低等優點，所以HBT漸被廣泛地使用於通訊用途上。

HBT的起源，是由William Shockley在1948年提出（專利編號為U.S. patent 2569347），詳細的理論推導及整體架構則是由H. Kroemer提出與建立；但直到70年代，HBT才真正實現於元件上；最早是利用液向磊晶（liquid-phase epitaxy，LPE）技術成長III-V族異質接面雙極性電晶體，隨著70年代中，分子束磊晶（Molecular Beam Epitaxy，MBE）及有機金屬化學氣相沉積（Metal-Organic Chemical Vapor Deposition，MOCVD）的技術成熟，使得HBT的磊晶品質上又邁進了一大步。

本論文主要對磷化銦鎵/磷化銦作兩方面的探討；第一部份是利用快速熱退火（Rapid Thermal Annealing，RTA）在700℃的環境，觀察基極層的濃度變化；原本預期基極濃度會增加一個數量級，但實際上僅增加原先的2~3倍左右，主要是由於氫的鈍化（hydrogen passivation），形成碳-氫鍵結合，使碳無法活化（activate）形成基極層的摻雜物（dopant）；不過，在RTA後，由於基極濃度的增加，減少了空間電荷複合（space-charge recombination）的機制，電流增益也由原先~10增加至~20。

第二部分則是將射極與基極間的空間區域（spacer）移除，以觀察元件特性的變化；結果證實當空間區域移除後，大幅度地減少了此區域的複合電流，使電流增亦由原先~10增加至~100以上；而由此部分的實驗亦證明了碳低擴散率（diffusivity）的特性。

Abstract
We investigate the effect of rapid thermal annealing on Carbon-doped InGaAs/InP heterojunction bipolar transistors（HBT's）.We predicted that, after 700℃ annealing, the p-type dopant can be increased by an order of magnitude, but the InGaAs base doping concentration shows that only about 2-3 fold dopant activation after RTA process. This could be attributed to hydrogen passivation during the growth. However, because of base dopant is activated, not additionally introduced, and less base current are spent on the space-charge recombination,higher gain can be anticipated for RTA device. Finally, we will also present the current gain which is over 100 by reducing the spacer thickness.

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