Arsenic adsorption and exchange with phosphorus on indium phosphide (001) have been studied by scanning tunneling microscopy, low-energy electron diffraction, and x-ray photoelectron spectroscopy. The surface phase diagram as a function of temperature has been obtained. At 285 °C, arsenic adsorbs on the InP $\sigma (2\mathrm{}\times 4)$ surface $(\mathrm{P}\mathrm{}\mathrm{coverage}=0.25\mathrm{}\mathrm{ML}),$ forming a disordered $(1\mathrm{}\times 4)$ with double layers of arsenic $(\mathrm{As}+\mathrm{P}\mathrm{}\mathrm{coverage}\sim 1.5\mathrm{ML}).\mathrm{}$ At 330 °C, arsenic adsorbs on the $\sigma (2\mathrm{}\times 4),$ producing a $(2\mathrm{}\times 1)$ structure with a complete monolayer of group-V dimers. By contrast, some phosphorus desorption occurs above 350 °C, allowing arsenic to displace the phosphorus in the top few layers and converting the $\sigma (2\mathrm{}\times 4)$ to the β2 and α2(2×4) reconstructions (As coverage 0.75 and 0.50 ML, respectively). Above 430 °C, arsenic exchange with InP yields an InAs $(4\mathrm{}\times 2)$ reconstruction. Quantitative analysis of the x-ray photoemission spectra has revealed that substitution of arsenic for phosphorus is limited to the top two to three surface bilayers.

• Received 22 October 2001

DOI:https://doi.org/10.1103/PhysRevB.65.205322