Investigations on Enhancement-Mode Al2O3-Dielectric AlGaN/GaN MOS-HFETs by Using Ozone Water Treatment

• Main Author: 黃泓熙
• Other Authors: 李景松
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/06834765151503644145

碩士 === 逢甲大學 === 電子工程學系 === 103 === In this thesis, AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors (MOS-HFETs) by using ozone water treatment technique are designed and investigated for a conventional HFET with the Schottky gate structure. A thin barrier structure was devised to achieve the enhancement-mode operation with the threshold voltage of 0.1 V. In order to resolve the problems of high gate leakage current and surface leakage current due to surface traps, high-k aluminum oxide (Al2O3) was used as the gate dielectric layer to improve the characteristics in comparison with the conventional HFETs. The device characteristics of the studied enhancement-mode AlGaN/GaN MOS-HFET (the referenced HFET) include maximum drain-source saturation current density (IDS, max) of 50.4 (23.1) mA/mm, maximum extrinsic transconductance (gm,max) of 31.6 (13.3) mS/mm, threshold voltage (Vth) of 0 (0.1) V, gate leakage current (Ig) of 2.2 × 10-4 (0.19) mA/mm at VGS = 60 V, two-terminal gate-drain breakdown voltage (BVGD) of -145 (-95) V, and three-terminal on-state drain-source breakdown voltage (BVDS) of 151 (98) V, respectively. From the experiment results, enhancement-mode operation and improved device performance have been successfully achieved for the present AlGaN/GaN MOS-HFET by using the ozone water treatment.