A comparison of liquid and gas phase surface preparation of III–V compound semiconductors for atomic layer deposition

Native oxide removal and surface termination of InAs(1 0 0) and InSb(1 0 0) using liquid and gas phase HF chemistries were studied using X-ray photoelectron spectroscopy. Aqueous HF etching removed the native oxides on InAs and produced elemental As, which reoxidized when exposed to air. On InSb the native oxides were not completely removed due to F-termination, which passivated the surface. Gas phase HF etching of InSb native oxide completely removed Sb2O5 producing a stoichiometric semiconductor surface terminated by F atoms on primarily In surface sites. On InAs gas phase HF completely removed As2O3 producing two surface stoichiometries. For the majority of HF to water molar ratios studied, a stoichiometric bulk metal and an As-rich overlayer were produced. For a lean HF composition, an As-rich bulk metal and In-rich overlayer were produced. Deposition of Al2O3 by atomic layer deposition (ALD) at 170 °C directly onto F-terminated InSb produced a chemically sharp Al2O3/InSb interface. ALD of Al2O3 on an In-rich overlayer on InAs resulted in an interfacial layer containing As-oxide.