Method of in situ photo induced evaporation enhancement of compound thin

Abstract

In situ evaporation of selected surface regions or layers of compound semiconductors is accomplished without breaking the growth system environment employing photo induced evaporation enhancement in chemical vapor deposition epitaxy. Intense radiation from an energy source desorbs or causes evaporation of consecutive monolayers of atoms or combined atoms from the surface crystal by thermal evaporation. The desorbed atoms from the growth surface are removed atomic layer by atomic layer in a fairly uniform and systematic manner and may be characterized as 'monolayer peeling' resulting in a morphology that is sculpturally smooth and molecularly continuous. In this sense, the method of this invention is analogous to erasing or the etching of crystal material and is the antithesis to laser deposition patterning wherein erasure after growth or reduced rate of growth during growth provide 'negative growth patterning'. In principal, then, this patternable negative growth process is coupled with a positive growth process for providing selective thinning regions of semiconductor layers in three dimensional crystal structures limited only by the functional capabilities of the growth reactor. Selective monotonic increasing and decreasing film thickness in situ can be accomplished while beam illumination remains stationary for a predetermined period of time with exposure of the growth surface accomplished through a patterned mask or, alternatively, while the beam spot or multiple beam spots are modulated and scanned across the growth surface of the film.