Electrical Analysis and Measurement of Ⅲ-ⅤCompound pHEMT

• Main Authors: Chi-Lin Han, 韓季霖
• Other Authors: Chung-Yuan Kung
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/10968862223101580090

碩士 === 國立中興大學 === 電機工程學系所 === 97 === Ⅲ-Ⅴ compound semiconductor devices are key parts of RF communication applications because they have advantages of high electron mobility, high working frequency, low RF loss, high linearity and low noise. It is so-called “pHEMT” for full name “Pseudomorphic High Electron Mobility Transistor”. It becomes the important modern RF active device as it has some characteristics: small size, low threshold voltage, low power consumption and less process requirements. In this study, device simulations were performed by TCAD simulators to research relationship between pHEMT DC characteristics and material structures. Three kinds of Schottky layer/channel layer/buffer layer material structures were simulated. They were AlGaAs/GaAs/GaAs, AlGaAs/InGaAs/GaAs and AlGaAs/InGaAs/AlGaAs, respectively. The result indicated that device electrical performance improved and 2DEG increased in channel layer which was replaced GaAs by InGaAs. Replacing GaAs by AlGaAs in buffer layer could increase conduction band discontinuousness at buffer layer junction. A actual pHEMT was also measured in this study. The threshold voltage of the pHEMT was 0.43V. The maximum transconductance was 320mS when VDS was 1.0V. It is possible to predict device characteristics with TCAD simulation before fabrication. The study results can be reference for future TCAD simulations to make physics models simulated corresponding with device characteristics measured. Then we can proceed with parameters analysis, database modeling and improve high frequency device design efficiency and quality.