Ge Flat Layer Growth on Heavily Phosphorus-Doped Si(001) by Sputter Epitaxy

We have investigated layer-by-layer Ge growth methods on phosphorus (P)-doped Si(001) with our sputter epitaxy method at a growth temperature (T G) of 350 °C. With the sputter epitaxy method, relaxed Ge islands are formed on P-doped 3.5 Ω cm Si with Ge–Si intermixing at the Ge/Si interface; however, a partially strained flat Ge layer is grown directly on P-doped 0.015 Ω cm Si. For comparison with a gas-source molecular beam epitaxy (GS-MBE) method using GeH4, Ge islands are formed on 0.015 Ω cm Si at T G = 350 °C. It has been suggested that the P dopants together with the sputter epitaxy method effectively suppress Ge islanding and induce Ge layer-by-layer growth.