Investigation of The Scaling HBT's Using Carrier Confinement and Passivation Layers

• Main Authors: Hsieh, Jin-Lung, 謝金龍
• Other Authors: Lour Wen-Shiung
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/70126026537602767254

碩士 === 國立海洋大學 === 電機工程學系 === 86 === In this thesis, we present two kind layers, passivation and carrier confinement layers of HBT. First, we report on the fabrications and characterizations of the InGaP/GaAs d-doped single heterojunction bipolar transistors (d-SHBT's) and the InGaP/GaAs/InGaP d-doped double heterojunction bipolar transistors (d-DHBT's) with InGaP passivation layers. Effect of passivation-layer thickness on the performance of the studied devices was investigated. Various passivation-layer thickness (0~100-nm-thick) were employed in the device fabrication to examine the device performance. Experimental findings show that both collector currents and current gains are enhanced at fixed base currents when a 40~60-nm-thick InGaP passivation layer for d-HBT's are used. We obtained a current gain and a collector current of 340 (300), 50 (42) mA at a base current of 200 uA for a d-SHBT with (and without) an InGaP passivation layer and current gain of 350 (280) at a base current of 100 uA for d-DHBT's with (and without) an InGaP one, respectively. And because of using a d-doped sheet to eliminate the potential spike at B-E and C-B heterojunctions, all d-HBT's exhibit extremely small offset voltages about 50 mV and collector current saturation voltages (knee voltages) smaller than 2.5 V. According to these results, InGaP/GaAs d- HBT's with InGaP passivation layers are suitable for high-gain, high-power, and high-frequency applications. Second, We proposed that a new InGaAs-based HBT with an InAlAs/InGaAs multiple-quantum-well (MQW) carrier confinement emitter layer in this study. Large-area (150 um*150 um) MQW- HBT's exhibit a much smaller offset voltage and a similar current gain as compared to a conventional heterostructure- emitter bipolar transistor (HEBT) with a bulk-InAlAs confinement emitter layer. The measured offset voltage and current gain are 75 (300) mV and 26 (21) in average for a MQW- HBT (HEBT). It is attributed the success to the reduction of effective conduction band offset. Furthermore, the DC current gain is nearly area-independent. All devices with large-area and small-area emitters exhibit current gains of 26 +- 3.