Characterization of Ga-doped solid phase — MBE silicon

Abstract

Controlled p-type doping of Si in the range 3×10 17-1×10 20 cm -3 has been achieved by varying the temperature of the Ga source in a molecular beam epitaxy (MBE) system. Amorphous Si layers were deposited on a clean Si surface at room temperature and in situ epitaxially crystallized at 575°C. Ion channeling measurements showed the crystalline quality of the epitaxial layers to be nearly as good as for bulk material up to a Ga concentration of 8×10 19 cm -3. The Ga depth profile in the layer was found to be nearly constant exhibiting a transition width to the substrate below 7 nm. Hole concentrations up to 1×10 20 cm −3 were achieved with Ga doping, which is higher than any reported value obtained in a MBE system.