Mechanism of Doping Gallium Arsenide with Carbon Tetrachloride DuringOrganometallic Vapor-Phase Epitaxy

摘要

The rates of decomposition of carbon tetrachloride (CCl4), triethylgallium (TEGa)and tertiarybutylarsine (TBAs), and the rate of GaAs film growth, were measured as a function of the process conditions during organometallic vapor phase epitaxy. In addition, the reaction of CC14 with the GaAs(001) surface was monitored in ultrahigh vacuum using infrared spectroscopy, temperature programmed desorption, and scanning tunneling microscopy. These experiments have revealed that CC14 adsorbs onto Ga sites, and decomposes by transferring chlorine ligands to other Ga atoms on the surface. Chlorine and gallium desorb from the surface as GaCl, while the carbon incorporates into the lattice. Triethylgallium is consumed by two competing reactions; GaAs film growth, and GaCl etching. Depending on the V/III and IV/III ratios and temperature, the etch rate can be high enough to prevent any GaAs deposition.