In this study, a SiO 2 /GaAs oxide bi-layer layer was used as the gate oxide in GaAs-based metal-oxide-semiconductor (MOS) devices. The GaAs oxide layer of the bi-layer layer was directly formed on the GaAs surface by using the photoelectrochemical (PEC) oxidation method. Some samples were thermally treated at 200 • C and 300 • C in O 2 ambience for 30 min. The surface state density of the oxide/GaAs interface with and without GaAs oxide thermal treatment was 7.2 × 10 11 and 7.9 × 10 11 cm −2 eV −1 , respectively. The GaAs MOS field effect transistors (MOSFETs) with the PEC-deposited GaAs oxide thermally treated showed an output current of 152 mA mm −1 at V DS = 2.4 V and V GS = 0 V and an extrinsic transconductance of 89 mS mm −1 .

Liquid phase deposition (LPD) grown InGaP native oxide near room temperature (~60oC) is demonstrated and investigated for the first time. A high oxidation rate (~80nm/hr) is obtained and checked by SEM and AES. The oxide is determined to be composed of InPO4 and Ga2O3 which are analyzed by the results of XPS measurement. Due to the presence of excellent quality of InGaP native oxide, high hydrogen (H2) sensitivity in output current of Pd/oxide/InGaP MOS Schottky diode is observed. Under the applied voltage of -1V and 50ppm H2/air, a high sensitivity of 1090 is obtained. In addition, an obvious variation of output current and a short response time due to the exposure to different H2 concentration are also achieved.

In this work, photoelectrochemical oxidation method was used to directly grown gate oxide of GaAs metal-oxide-semiconductor field effect transistor. The I DS-V DS and g m-V GS characteristics of the GaAs MOSFETs were measured. For biasing at V DS =2.4V and V GS =0V, an output current density of 101mA/mm was obtained. The associated extrinsic transconductance of the GaAs MOS-FETs was 65mS/mm.