Growth and Interface Evolution of HfO2 Films on GaAs(100) Surfaces

Abstract

The initial film growth (2–100 cycles) and the interface evolution of thin films on GaAs surfaces were investigated for an atomic layer deposition chemistry that utilizes tetrakis(ethylmethyl) amino hafnium and at . Starting surfaces include native oxide and HF or -etched substrates. X-ray photoelectron spectroscopy shows that deposition on native oxide GaAs surfaces results in the gradual consumption of the arsenic and gallium oxides. Arsenic oxides are easier to remove, leaving some metallic arsenic–arsenic suboxide at the interface. The removal of the gallium oxides is slower, and some residual and are detected after 100 process cycles. High resolution transmission electron microscopy confirms the presence of an almost sharp interface for the 100 cycle (12 nm) film and indicates that the as-deposited film is polycrystalline. The depositions on either HF or -etched substrates result in a sharp interface with very little residual gallium oxide and arsenic suboxide present. Rutherford backscattering spectroscopy shows that steady-state growth comparable to that achieved on is reached after ALD cycles for all GaAs surfaces; however, high initial surface activity is detected for the etched surfaces.