Thermal reactions of phosphine with Si(100): a combined photoemission and scanning-tunneling-microscopy study

• Published in: Surface science 1999-03, Vol.424 (1), p.7-18
• Main Authors: Lin, D.-S., Ku, T.-S., Sheu, T.-J.
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Chemistry; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; General and physical chemistry; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Phosphine; Photoemission; Physics; Scanning tunneling microscopy; Silicon; Solid surfaces and solid-solid interfaces; Solid-gas interface; Surface physical chemistry; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(98)00943-1

This study investigates the adsorption and thermal decomposition of phosphine (PH 3) on the Si(100)-(2×1) surface. The adsorption species, dissociation reactions, atomic ordering, and surface morphology of the phosphine/Si(100) surface at temperatures between 300 and 1060 K are examined by scanning tunneling microscopy (STM) and high-resolution core-level photoemission spectroscopy employing synchrotron radiation. The P 2p core level spectra clearly indicate that phosphine molecularly adsorbs at room temperature and partially dissociates into PH 2 and H on a time scale of minutes at low (15 Langmuirs (L, 1 Langmuir=10 −6 Torr s −1) of phosphine on the Si(100)-(2×1) surface at room temperature produces a saturated and disordered surface. The total amount of P on the saturated surface is ∼0.37 ML as calibrated by the P 2p photoemission intensity. Successive annealing of the saturated surface at higher temperatures converts PH 3 into PH 2, converts PH 2 to P–P dimers, and causes the desorption of PH 3. These processes become complete at ∼700 K, and the resulting surface is a H/Si(100)-(2×1) surface interspersed with one-dimensional P–P islands. Desorption of hydrogen from that surface occurs at ∼800 K, and is accompanied by partial displacement of P with Si atoms on the substrate. At 850 K, the Si(100) surface, interspersed with 0.22 ML of two-dimensional islands, is a random alloy of nominal 0.5 ML Si–P heterodimers and 0.5 ML Si–Si dimers.