Volker Graf

GaInAs/InP selective area metalorganic vapor phase epitaxy for one‐step‐grown buried low‐dimensional structures

The selective area epitaxy of GaInAs/InP layers grown by low‐pressure metalorganic vapor phase epitaxy through SiO2 patterned masks was investigated. The layers are found to develop mesa structures limited by {111} and (100) facets outside of the opened mask, and perfect selective epitaxy is obtained. The absence of GaInAs growth on {111} facets allows the fabrication of very narrow buried GaInAs layers in a single growth step. For both materials, the growth rates are found to depend strongly on the mask geometry owing to surface diffusion of the reactant species from the no‐ or low‐growth SiO2 mask and {111} facets toward (100) surfaces. A detailed quantitative analysis is made to identify the critical parameters that control the growth behavior, and a model is described from which the upper limit of the growth rates for any mask design can be calculated. Low‐temperature cathodoluminescence measurements show strong emission of the buried GaxIn1−xAs layers and indicate local stoichiometry variations Δx≂±5...

Buried GaInAs/InP layers grown on nonplanar substrates by one‐step low‐pressure metalorganic vapor phase epitaxy

Growth of GaInAs/InP layers on nonplanar substrates by low‐pressure metalorganic vapor phase epitaxy has been investigated using InP substrates patterned with [011] and [011] oriented grooves and mesas. For a wide range of growth parameters we find that GaInAs does not grow on {111}A and {111}B surfaces whereas InP grows on all available crystal planes. This allows very narrow GaInAs layers to be embedded in InP within one growth step. We find that the growth rate on the (100) surface of a mesa increases for both materials when the mesa width is reduced below ∼2 μm. The results are explained with a growth model where crystal facet‐dependent surface catalyzed reactions dominate the growth on a microscopic scale. These lead to blocking of low growth rate planes for the adsorption of arriving species and to local redistribution of adsorbed molecules by surface diffusion.

Shallow implants into GaAs

Scaling of lateral device dimensions into the submicron range also requires the reduction of the vertical dimensions. Shallow ion implantation is necessary for channel formation of submicron MESFETs. Partial-ion-channeling tails were found for energies below 60 keV, and resulted in a significantly broader profile than predicted by LSS theory. Diffusion effects are investigated by comparing SIMS profiles from as-implanted, rapid thermal and furnace-annealed samples. Comparison of the CV and SIMS profiles gives information on the annealing behavior, and allows the definition of a differential activation efficiency. Our investigations showed that for vertical scaling, a simple reduction of implant energy is not enough. We found several procedures which yield shallower profiles.