Formation of hydrogen-related shallow donors in Ge1-xSix crystals implanted with protons

It is found that shallow hydrogen-related donors are formed in the proton-implanted dilute Ge1-xSix alloys (0≤x≤0.031) as well as in Si-free Ge samples upon heat-treatments in the temperature range 225-300 degrees centigrade. The maximum concentration of the donors is about 1.5·1016 cm-3 for a H+ implantation dose of 1015 cm-2. Formation and annihilation temperatures of the proton-implantation-induced donors do not depend on the Si concentration in Ge1-xSix samples. However, the increase in Si content has resulted in a decrease of the concentration of the H-related donors. The possible origin of the H-related donors and mechanisms of Si-induced suppression of their formation are discussed. (authors)