Impact of arsenic species (As2 As4) on the relaxation and morphology of step-graded in Asx P1-x on InP substrates

The influence of arsenic species (As2 or As4) on compositionally graded In Asx P1-x buffer layers (x=0.15-0.8) grown by molecular beam epitaxy on InP is investigated. It was found that As2 has a higher incorporation rate than As4. Anisotropic strain relaxation occurs for samples grown with As4, with higher relaxation along [110] and lower relaxation along [1-10]. Relatively high and isotropic strain relaxation occurs for buffers grown with As2. The observed mosaic broadening is much greater when using As2. Atomic force microscopy morphological features are consistent with the strain relaxation results. Strong corrugations along [1-10] dominate the surface of films grown with As4, while grainy surfaces occur with As2. The use of As4 increased the overall surface roughness. The authors interpret these results with a simple model: the higher incorporation rate of As2 enables In to incorporate more uniformly in the two perpendicular 〈110〉 directions, while the lower incorporation rate of As4 decreases this uniformity. The different incorporation rates of In in the [110] and [1-10] directions may result in diverse morphologies and strain relaxation induced by arsenic spices. © 2007 American Vacuum Society.

Duke Scholars

Author April S. Brown Electrical and Computer Engineering