Some chemical, structural, and electronic properties of (NH4)2Sx-treated InP(001) surfaces have been studied using x-ray photelectron spectroscopy, x-ray photoelectron diffraction and reflection high-energy electron diffraction. A (2×1) surface reconstruction is observed for substrates heated in vacuum at a transition temperature of about 200–350 °C. Sulfur atoms are only bonded to indium atoms and the exchange between phosphorus and sulfur occurs in the first five atomic planes leading to the formation of an InP1−xSx pseudomorphic overlayer. The sulfur surface concentration varies from about 0.85±0.15 after annealing at 350 °C to 0.5±0.15 monolayer at 550 °C. The sulfidation treatment results in (2×1) reconstructed surfaces of high thermal stability up to 560 °C and of high chemical stability. Unpinned ultraclean surfaces, free of carbon and oxygen, are obtained after vacuum annealing at 550 °C.

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Using x-ray photoelectron spectroscopy (XPS), it is demonstrated that noncrystalline thin oxide layers grown on InP by ultraviolet (UV)/ozone oxidation are composed of a single phase of phosphate average composition InP0.5O2.75 which do not exist as crystalline compounds. The ability of nonstoichiometric InP native oxides to passivate InP surfaces is discussed on the basis of these new findings.

Hydrogen ion cleaning procedures of InP(100) surfaces have been studied and the effect of hydrogen on carbon and oxygen contaminations were particularly investigated. The induced structural surface modifications were studied by x-ray photoelectron spectroscopy and in situ reflected high-energy electron diffraction just after ion bombardment and after annealing under an arsenic overpressure. Results show that cleaning with hydrogen ions leaves an indium-rich surface layer on the InP surface. After hydrogen ion bombardment, structural changes of the surface occur and their irreversibility after As stabilization depends on the hydrogen dose. If this dose does not exceed a critical value of about 3×1016 ions/cm−2, the structural properties of the InP surface can be restored after thermal annealing under arsenic overpressure. However, both unannealed and annealed surfaces show a strong pinning of the Fermi level, with the creation of defects 0.25 eV below the minimum conduction band, which indicates poor electronic properties always after hydrogen ion bombardment.