Formation of Hydrogen-Related Shallow Donors in Ge1-xSix Crystals Implanted with Protons

Abstract

It is found that shallow hydrogen-related donors are formed in proton-implanted dilute Ge1-хSiх alloys (0 ≤ x ≤ 0.031) as well as in Si-free Ge samples upon heat-treatments in the temperature range 225-300oC. The maximum concentration of the donors is about 1.5×1016 cm-3 for a H+ implantation dose of 1×1015 cm-2. The temperature range of formation of the protonimplantation- induced donors is the same in Ge1-xSix samples with different Si concentration. However, the increase in Si content results in a decrease of the concentration of the hydrogenrelated donors. It is argued that the H-related donors could be complexes of Ge-self-interstitials with hydrogen atoms. The observed decrease in the concentration of the donors with an increase in Si content in the Ge1-xSix samples is associated with interactions of mobile hydrogen atoms with Si impurity atoms. Such interactions reduce the number of implanted hydrogen atoms that can be involved in defect reactions resulting in the formation of H-related shallow donors.