Dose rate and temperature dependence of Ge range profiles in Si obtained by channeling implantation

The strong influence of dose rate and implantation temperature on the dose dependence of the shape of Ge channeling implantation profiles is demonstrated for the first time. Applying a focused ion beam (FIB) system allows the use of a very high (10¹⁸ cm^-2s^-1) and a very low (10¹⁰-10¹¹ cm^-2s^-1) dose rate. Implantations are performed at R.T. and at 250°C. At the high dose rate and R.T. the dose rate dependence of the profile shape is found to be most pronounced. Atomistic computer simulations using a relatively simple damage buildup model can explain the effects observed. It is shown that at R.T. defect relaxation processes can last up to 1 s, which is longer than assumed so far. The lifetime of implantation defects at 250°C is estimated to be in the order of 10s.