Development of a Heterojunction Structure Detector in the Submillimeter Wave Region

本文研究了一种异质结双极晶体管（HBT）结构探测器，作为一种新型的毫米波和亚毫米波探测器。在100GHz到1THz的频率范围内，与肖特基势垒二极管（SBD）相比，该探测器可能具有更高的灵敏度。首先，我们对异质结结构探测器进行了理论模拟研究，考虑了传输时间和寄生元件，并在微波区使用硅双极晶体管进行了模型实验。在低频范围内获得了5 × 10^5 V/W的视频灵敏度，远高于二极管检波器。并且，即使在比晶体管截止频率（ft）高约8倍的频率下，也能获得2 × 10^3 V/W的灵敏度。理论仿真结果表明，基极和校正器之间的寄生电容对检测器和放大器工作的影响不大。这一结果为SMM波探测器的发射极、基极、校正结构的特殊设计提供了可能。我们设计了专门用于SMM探测器的发射极基极结构和AlGaAs/GaAs半导体层及其杂质结构。并且我们已经用MBE方法精确地完成了半导体沉积。目前，探测器的制作工艺不断得到改进，采用光刻法、ECR等离子体刻蚀法和选择性湿法刻蚀法。

A heretojunction bipolar transistor (HBT) structure detector has been studied as a new type detector in the millimeter (MM) and submillimeter (SMM) wave region. The detector which may have much higher sensitivity compared to the Schottky Barrier Diode (SBD) in the frequency range from 100GHz to 1THz.Primarily, we have studied the heterojunction structure detector theoretically as a simulation taking into account of transit time and parasitic elements, and experimentally as a model experiment using a Si bipolar transistor in the microwave region.The video sensitivity of 5x10^5 V/W has been obtained in the low frequency range, which is much higher than that of the diode detector. And also, the sensitivity of 2x10^3 V/W is obtained even at the frequency of about 8 times higher than the cutoff frequency (ft) of the transistor. The influence of the parasitic capacitance between base and corrector is not high for detector operation, not for amplifier operation, as predicted by the theoretical simulation. The result has suggested a possibility of special design of the emitter, base, corrector structure for the SMM wave detector.We have designed the emitter base structure specially for the SMM detector and AlGaAs/GaAs semiconductor layer and impurities structure for it. And we have completed semiconductor deposition precisely using the MBE method.Now the fabrication process of the detector are improved and going on using photolithography, ECR plasma etching, and selective wet etching.