FORMATION OF SUPER AS-RICH GAAS(100) SURFACES BY HIGH-TEMPERATURE EXPOSURE TO ARSINE

We report that arsine exposures between 100 and 350-degrees-C will produce "super" As-rich surfaces [arsenic coverages of up to approximately 1.7 monolayers (ML, where 1 ML = 6.26 x 10(14) atoms cm-2)] of GaAs(100) that exhibit a c(4 x 4) low energy electron diffraction pattern. Temperature programmed desorption studies show that after AsD3 exposures of up to 2.6 x 10(6) L (1 L = 1 x 10(-6) Torr s) to the Ga-stabilized surface, three excess As desorption speaks are observed with maxima at 440, 480, and 570-degrees-C. As4 desorption is detected from the lowest temperature state, while the other states desorb primarily as As2. The significance of these results for the understanding of the atomic layer epitaxy process is addressed.