p-type doping of germanium grown by molecular beam epitaxy on Ge(100) substrates

Abstract

We have conducted studies of p-type doping using gallium and boron of germanium grown on germanium (100) substrates by molecular-beam epitaxy. Excellent germanium films have been grown on Ge substrates with little demarcation of the substrate-epi interface. Gallium doping of germanium takes place through an adlayer at the growth front, and between growth temperatures of 450 °C and 550 °C successful p doping of germanium by gallium with good activation has been accomplished. A first-order kinetic incorporation model has been used to describe the behavior of gallium in germanium as a function of surface coverage and growth temperature. Boron is an excellent p dopant in germanium with good activation at high concentrations and sharp transition profiles.