Autocatalytic Dissociative Adsorption of Imidazole on the Ge(100)‑2 × 1 Surface

The adsorption of imidazole on the Ge(100)-2 × 1 surface is studied with ultrahigh vacuum infrared spectroscopy experiments and density functional theory calculations. Imidazole datively bonds to the surface through its pyridinic nitrogen at low coverage, while dissociation of the pyrrolic N–H is observed upon larger exposure. The coverage-dependent change in the product distribution is explained by autocatalytic activation of the dissociative adsorption via interaction between adjacent imidazole adsorbates. These results suggest an alternative explanation for the previously studied adsorption chemistry of bifunctional ethylenediamine on Ge(100)-2 × 1

Autocatalytic Dissociative Adsorption of Imidazole on the Ge(100)‑2 × 1 Surface

The adsorption of imidazole on the Ge(100)-2 × 1 surface is studied with ultrahigh vacuum infrared spectroscopy experiments and density functional theory calculations. Imidazole datively bonds to the surface through its pyridinic nitrogen at low coverage, while dissociation of the pyrrolic N–H is observed upon larger exposure. The coverage-dependent change in the product distribution is explained by autocatalytic activation of the dissociative adsorption via interaction between adjacent imidazole adsorbates. These results suggest an alternative explanation for the previously studied adsorption chemistry of bifunctional ethylenediamine on Ge(100)-2 × 1

Passivation of InGaAs(001)-(2 × 4) by Self-Limiting Chemical Vapor Deposition of a Silicon Hydride Control Layer

A saturated Si–H_<i>x</i> seed layer for gate oxide or contact conductor ALD has been deposited via two separate self-limiting and saturating CVD processes on InGaAs(001)-(2 × 4) at substrate temperatures of 250 and 350 °C. For the first self-limiting process, a single silicon precursor, Si₃H₈, was dosed at a substrate temperature of 250 °C, and XPS results show the deposited silicon hydride layer saturated at about 4 monolayers of silicon coverage with hydrogen termination. STS results show the surface Fermi level remains unpinned following the deposition of the saturated silicon hydride layer, indicating the InGaAs surface dangling bonds are electrically passivated by Si–H_<i>x</i>. For the second self-limiting process, Si₂Cl₆ was dosed at a substrate temperature of 350 °C, and XPS results show the deposited silicon chloride layer saturated at about 2.5 monolayers of silicon coverage with chlorine termination. Atomic hydrogen produced by a thermal gas cracker was subsequently dosed at 350 °C to remove the Si–Cl termination by replacing with Si–H termination as confirmed by XPS, and STS results confirm the saturated Si–H_<i>x</i> bilayer leaves the InGaAs(001)-(2 × 4) surface Fermi level unpinned. Density function theory modeling of silicon hydride surface passivation shows an Si–H_<i>x</i> monolayer can remove all the dangling bonds and leave a charge balanced surface on InGaAs