This paper uses H2O2 oxidation technique to grow Al2O3 on AlGaN/GaN heterostructure. The H2O2-grown-Al2O3 is served as a sensing membrane and a surface passivation layer. The contact angle of the ion-sensitive field-effect transistor (ISFET) with the H2O2-grown-Al2O3 is improved from 66.5° to 40.6° and this phenomenon indicates that the hydrophile characteristic is improved after the H2O2 treatment. The drain-source current (IDS) is improved ∼ 32% after the H2O2 oxidation due to the passivation effect. In addition, extrinsic transconductance (gm) characteristics of the transistors are investigated. The pH sensitivity is also improved from 41.6 to 55.2 mV/pH for the ISFET with H2O2-grown-Al2O3. Furthermore, the ISFET with the H2O2 treatment exhibits better transient characteristics compared with the ISFET without the H2O2 treatment. The sensitivity parameter (β) and the relationship between surface potential (ψs) and pH value are investigated by theoretical calculation. The hysteresis phenomenon and the drift effect can be improved using the present H2O2-grown Al2O3 as the sensing membrane and the passivation layer.
All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering