Joint Diffusion of Gallium and Phosphorus Atoms in Silicon

Abstract

It was found that the diffusion of gallium and phosphorus atoms from the gas phase into silicon not only compensates, but also a particular interaction with each other. Elemental analysis on a scanning electron microscope showed that gallium and phosphorus atoms are present on the silicon surface after diffusion and processing in similar concentrations. Investigation of the concentration distribution of charge carriers over depth shows that, upon joint diffusion, the solubility of gallium increases by one order of magnitude. In this case, the mobility of charge carriers decreased 3–4 times. Based on the data obtained, the concentration (~ 1019 cm-3) of neutral complexes [Ga-P+] and their formation energy (~ 0.62 eV) were calculated. The results obtained can be associated with the electrostatic interaction of gallium and phosphorus ions during diffusion, as a result of which, the concentration distribution of impurities changes, as well as the formation of quasineutral complexes of the [Ga-P+] type in the silicon lattice.