Fabrication and Analysis of Enhancement Mode AlGaN/GaN MOSHEMTs Using Fluoride-based Plasma Treatment

• Main Authors: Sin-Yi Yin, 尹新逸
• Other Authors: Chao-Hsin Wu
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/46959578248092396087

碩士 === 國立臺灣大學 === 光電工程學研究所 === 103 === In this thesis, we investigated the effect of gate recess process and oxide layer deposition on DC characteristics of AlGaN/GaN HEMT first. Threshold voltage of AlGaN/GaN HEMTs can be shifted by gate recess process and oxide layer deposition. Gate recess process and oxide layer deposition also affect off state current and surface traps effect. Only for process development and didn’t do further research in this chapter because of poor wafer quality. In order to reduce the loss of switch, the development of normally off GaN FETs is the major direction of research. We using fluoride-based plasma treatment on different epitaxy structures to fabricate enhancement mode HEMTs show a performance compare with the depletion mode HEMTs. Threshold voltage of AlGaN/GaN HEMTs can be shifted from -1.3 V to 0.45 V. We deposited 10 nm Al2O3 as oxide layer of AlGaN/GaN MOSHEMTfor the higher gate voltage applicable and reduce gate leakage current. The damage caused by fluoride treatment can be recovered by post metallization anneal while shows drain current density 1.5 times improvement. We also investigated the engineering of interface traps cause threshold voltage shift under different gate bias operation and CV measurement. Current collapse phenomena are also observed by using gate lag pulse measurement.