Electrical properties of Sb implanted Si_1-xGe_x alloy layers

Electrical properties of Sb implanted strained Si_1-xGe _x alloy layers are reported. Two sets of Si_1-xGe _x epilayers with compositions of x=0.08 and 0.18, MBE grown on (100)Si substrates, were implanted at room temperature with Sb⁺ ions at energies of 200 and 100 keV, respectively, and doses of 10¹³ and 10¹⁵ cm^-2. Secondary-ion mass spectrometry and spreading resistance profiling measurements show that Sb implantation, with a dose below the critical value for amorphization (10¹³ cm^-2), formed a p-type region upon annealing at 500°C. Only higher temperature anneals transformed the implanted layer into the expected n-type doping. Maximal values of electrical activity (45±10%) and mobility were obtained in this case only at temperatures around 800-900°C. For the high dose implantation (10¹⁵ cm^-2), it was found that the highest activation efficiency at the implantation profile peak was obtained at 500-600°C, while at the end-of-range region the activation efficiency was very low.