The role of atomic surface structure in the metalorganic chemical vapor deposition of III-V compound semiconductors

The atomic structure of gallium arsenide and indium phosphide (001) surface s in the metalorganic chemical vapor deposition (MOCVD) environment has bee n characterized in situ by scanning tunneling microscopy and infrared spect roscopy. During growth at V/III ratios above 10, these films exhibit simila r surface structures. They are terminated with alkyl groups, hydrogen atoms and group V dimers (As or P) adsorbed on top of a complete layer of group V atoms. As the V/III ratio decreases, the exposed arsenic and phosphorous atoms desorb from the surface. On gallium arsenide, this occurs through a p hase transition, involving gallium out-diffusion and surface roughening. By contrast, on InP, the underlying phosphorous atoms simply form rows of dim ers, yielding a smooth, continuous layer.