HYDROGEN CHEMISORPTION AND REACTION ON GAAS(100)

We have studied the chemisorption of atomic hydrogen and deuterium on gallium-rich (4x6) and arsenic-rich c(2x8) GaAs(100) reconstructed surfaces using temperature programmed desorption (TPD). Molecular hydrogen (specifically D2) desorption from the gallium-rich (4x6) surface exhibits a peak at 480–510 K, depending on the initial coverage. By comparing results from the different reconstructions we conclude that the desorption of molecular hydrogen primarily arises from surface GaHxspecies. The arsenic-rich c(2x8) surface yields a small amount of molecular hydrogen desorption around 660 K, apparently arising from surface AsHxspecies. In addition to molecular hydrogen, chemisorbed arsine is detected desorbing from both reconstructions around 330–340 K. This result indicates that atomic hydrogen can etch the GaAs surface. For the maximum exposure studied, ~ 15% of the surface arsenic on the arsenic-rich c(2X 8) surface is converted to arsine. © 1990, American Vacuum Society. All rights reserved.