FLUX MASKING AND THICKNESS UNIFORMITY IN MOLECULAR-BEAM EPITAXY

We suggest that properly designed masks altering the rotation-integrat ed flux arriving at the substrate may be used to improve thickness uni formity in a variety of crystal growth techniques. As an illustration, we calculate the dimensions of the mask required to produce a perfect ly uniform flux for a single group-III species in single- and multiple -wafer III-V molecular beam epitaxy. Estimates of the detrimental role of errors in mask machining and position are provided and schemes for correcting flux nonuniformities for multiple sources are suggested. O ur results imply that flux masking can lead to significant uniformity improvements for growth on single or multiple wafers. (C) 1995 America n Vacuum Society.