Surface Passivation of GaAs Substrates with SiO2 Deposited Using ALD

Feasibility of using atomic layer deposited (ALD) silicon dioxide (SiO2) as interface passivation layer in bulk-GaAs and epitaxial-GaAs (epi-GaAs) substrate is studied. The interfacial reaction mechanisms of ALD SiO2 on bulk-GaAs and epi-GaAs are studied using x-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and electrical measurements. Higher oxidation states of Ga (Ga2+, Ga3+) and As-O bonding are found to get effectively suppressed in ALD SiO2/GaAs structures after post deposition annealing. Capacitance-voltage characteristics of the TaN/ALD SiO2/p-GaAs gate stack show low hysteresis (similar to 30 mV) compared to ALD HfO2 on bulk p-GaAs. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3615963] All rights reserved.