本論文主要研究內容在於磷化銦雙異質接面雙極性電晶體的製作與特性分析。利用苯並環丁烯（BCB）的特性，發展出一套以BCB做為鈍化層的製程技術，以簡化製程。以此製程技術製作的InP-based HBT`s於直流的表現方面，可以有效抑制基極表面復合電流的產生，在相同的集極電流下，獲得較高的電流增益，使G值大於1（G = Ap. / Au.p. = ∫ß passivated HBT d(log(IC)) / ∫ß unpassivated HBT d(log(IC))）。 利用簡單、容易成長的結構，陡峭接面（abrupt junction），配合基-射極（B-E）與基-集極（B-C）間隔層（spacer layer）與N＋ InP layer 來提升元件的特性：不但能有效降抑制基極擴散（Base out-diffuse），降低導通電壓，提升電流增益；亦能控制B-C接面導通電壓，在有效抑制電流阻擋效應（current blocking effect）的情形下，將 off-set voltage 拉低至0.1V以下，而且崩潰電壓可以維持在5V以上。而將基極與集極的厚度降低，可以獲得108 GHz的截止頻率(2x20μm2)。 InGaAs spacer layer at base-collector junction of InGaAs/InP double heterojunction bipolar transistor (DHBT) is employed widely for lowering current blocking effect. The thickness of this spacer layer has to be optimized to reduce current blocking while maintain a reasonably low VCE offset voltage and high breakdown voltage. Since the offset voltage is partly resultant from the difference between the turn-on voltages of base-emitter and base-collector junction, it is our intention to design a collector structure so that the base- collector junction turn-on voltage can be increased to match that of the base-emitter junction. Parameters, such as layer thickness and doping concentration, are investigated experimentally as well as theoretically.
