Pre-atomic layer deposition surface cleaning and chemical passivation of (100) In(0.2)Ga(0.8)As and deposition of ultrathin Al(2)O(3) gate insulators

Abstract

We have developed and tested the efficacy of a method for pre-atomic layer deposition (ALD) surface preparation that removes native oxides from the (100) In(0.2)Ga(0.8)As surface and provides a clean starting surface for ALD of ultrathin Al(2)O(3) layers. Successive wet etching by aqueous HCl and NH(4)(OH) solutions and in situ pre-ALD thermal desorption of residual elemental As were performed. Photoelectron spectra obtained after ALD of Al(2)O(3) on In(0.2)Ga(0.8)As prepared by this method revealed that the interface was free of In, Ga, and As oxides. The resultant metal-oxide-semiconductor capacitors with Pt electrodes exhibited capacitance-derived equivalent oxide thicknesses as small as 1.8 nm.