Fabrication of GaN/AlGaN Schottky Contact Field-Effect Devices

Abstract

In this thesis AlGaN/GaN heterostructures grown by metal organic chemical vapor deposition (MOCVD) are proposed to fabricate field-effect devices including Schottky diode type hydrogen gas sensor and high electron mobility transistor (HEMT) For hydrogen gas sensors the Pd metal is chosen as Schottky contacts metal to detect hydrogen gas Also the hydrogen peroxide (H2O2) surface treatment is used in this work Based on the strong oxidation property a thin AlOx layer could be formed by an appropriate immersion of H2O2 solution The formed AlOx layer increases the effective adsorption sites and remarkably improves the related hydrogen gas detection capability Hydrogen sensing behaviors of the studied devices are investigated by sensing response and response time under different gas concentrations For AlGaN/GaN HEMTs an SiO2 dielectric layer prepared by R F sputtering is implemented in this study The formed SiO2 dielectric layer could decrease the surface state and suppress the current collapse In addition a stack dielectric structure of AlOx/SiO2 is fabricated and studied in this work The insertion layer of AlOx is achieved by an H2O2 wet chemical surface treatment The stack dielectric layers could further improve device performance

Date of Award	2016 Aug 2
Original language	English
Supervisor	Wen-Chau Liu (Supervisor)