Direct synthesis of II3-V2compound semiconductors by the heterovalent exchange reaction

Abstract

Abstract It is shown that it is possible to synthesize thin films of the II3-V2 compound Zn3As2 by the heterovalent exchange reaction (HER) of dimethylzinc in H2 with GaAs substrates at 350°C. These films are of a very high structural quality, being both epitaxial and highly ordered in nature as shown by an extensive transmission electron microscopy study. Using comparisons with simulated images and diffraction patterns, it is shown that the Zn3As2 formed is of the low-temperature α phase, which is stable below about 190°C. The lack of free gallium present on the surface suggests that methyl radicals are responsible for transport of exchanged gallium into the vapour phase. The high structural quality of the layers grown by this technique suggests that the HER is a promising method of circumventing the usual problems of mismatched epitaxial growth and that a wide range of thin-film materials may possibly be grown.