Quality optimization of liquid phase deposition SiO2 films on gallium arsenide

For liquid phase deposition (LPD) at room temperature (similar to 40 degreesC) of silicon dioxide (SiO2) on gallium arsenide (GaAs) substrate, this study correlates growth solution concentrations with resultant film quality. This LPD process pretreats the GaAs substrate with ammonia solution kept at pH = 11-12, thereby generating OH radicals on the GaAs surface which enhance SiO2 deposition. It is found that growth conditions such as low hydrofluosilic acid concentration, proper boric acid concentration, and low growth rate play important roles in optimizing deposited film quality. When LPD-SiO2/GaAs grown at optimum conditions is used to fabricate a metal-oxide-semiconductor field effect transistor, the transconductance, g(m), is about 68, the drain current, I-DS, is 10 mA for gate oxide thickness = 20 nm and W/L = 40/2. LPD-SiO2/GaAs grown at the proposed conditions equals or exceeds the quality of competing techniques, with a process that proceeds rapidly at room temperature and pressure, with inexpensive equipment. (C) 2000 Elsevier Science Ltd. All rights reserved.