GaN-Based Chemical Sensors with Specific Surface Treatments

Abstract

In this study the native oxide (GaxOy) layer is formed on GaN surface of GaN/AlGaN/GaN high-electron-mobility transistor (HEMT) by immersing into H2O2 solution The native oxides on GaN surfaces can improve the sensing capability on hydrogen ions and gases For hydrogen ion sensing ion-sensitive field-effect-transistor (ISFET) devices prepared by hydrogen peroxide (H2O2) treatment on GaN/AlGaN/GaN HEMT structure were investigated The native oxides on GaN surfaces were grown by immersing into H2O2 solution at 300 K The studied ISFET devices with native oxides were applied to measure the changes of the ion concentrations in an ambient electrolyte The pH sensitivity of voltage and current was 53 68 mV/pH and -25 24 μA/pH for GaxOy surfaces In addition the corresponding long-time drift variation (0 63 μA/hr) and hysteresis property (0 4 mV) of studied ISFET device were investigated Compared with the conventional pH glass electrodes the studied ISFETs have many advantages of high sensitivity short response time small size simple structure easy integration and high compatibility with CMOS technology Therefore the studied ISFETs with native oxide sensing films are very promising for biological and chemical sensor applications For gas sensing Schottky-type gas sensors prepared by H2O2 solution on GaN/AlGaN/GaN structure were investigated Pd and Pt were chosen as Schottky contacts metal to detect hydrogen and ammonia gas respectively The main purpose is to compare the gas sensing properties of devices with and without H2O2 treatment Hydrogen and ammonia sensing behaviors of studied devices are investigated in terms of sensing response and response time with different gas concentrations Based on excellent results and compatibility of CMOS fabrication techniques of studied devices the studied devices show the promise for the integration of high-performance sensor and micro-electro-mechanical system (MEMS)

Date of Award	2014 Jul 16
Original language	English
Supervisor	Wen-Chau Liu (Supervisor)