SR-stimulated etching and OMVPE growth for semiconductor nanostructure fabrication

Synchrotron radiation- (SR-)stimulated etching and selective area growth by organometallic vapor phase epitaxy were performed to form an ordered array of InP crystals on SiO2-patterned InP (001) substrate. The SR-stimulated etching was used to pattern the SiO2 film, because photochemical reaction using SR was expected to provide smooth surfaces, vertical side walls and fine patterning. In the first place, we investigated the basic properties of the SR-stimulated etching by using a mm-size pattern of SiO2 mask. The etched depth was observed to increase linearly with the irradiation dose. It was found that the etching depth was controlled very accurately. Next, we used μm-size patterns of SiO2 masks for fabricating the ordered array of InP crystals. In a atomic force microscope image of the sample after etching, a steep side wall was observed. However, the etched surface was not smooth, contrary to our expectation. Moreover, some dust were observed on the surface. From this dust it was found that the SR-stimulated etching had a resolution of ≤100 nm at most.