ATOMIC-FORCE MICROSCOPY STUDY OF ORDERED GAINP

This letter presents an experimental study, using high-resolution atomic force microscopy, of the nature of the steps on the surface of GaInP layers lattice matched to GaAs substrates. The substrates were intentionally misoriented from the (001) plane by angles of 3°, 6°, and 9°toward [1̄10] and the layers were grown by organometallic vapor phase epitaxy at temperatures of 570, 620, and 720°C. The surfaces consist of a mixture of monatomic (2.9 Å) [110] steps and [110] oriented supersteps with a distribution of heights from 2 to approximately 17 monolayers. The height of the largest steps increases monotonically with increasing misorientation angle. The supersteps are apparently formed by bunching of monatomic steps producing high index (11n) surfaces (n=4 to 7). This leaves relatively large (several hundred Å) (001) facets adjacent to the supersteps. The superstep height increases and the density decreases with increasing growth temperature. An attempt is made to correlate the supersteps to the degree of order and the microstructure of the ordered domains.© 1995 American Institute of Physics.