Annealing behaviour of excess carriers in neutron-transmutation-doped silicon

In neutron-transmutation-doped silicon wafers excess carriers are clearly generated over the transmuted phosphorus atoms. The generation occurs for annealing temperatures above 900 oC. The maximum percentage of excess carriers obtained is about 24.5% of the final carrier concentration. Due to the difference in energy of generation and removal, the excess carriers can be removed by annealing above 800oC. The radiation damage responsible for generation of excess carriers is fairly thermostable in the range of annealing temperatures below 800 oC. From deep-level transient spectroscopy measurements, it is found that the radiation damage remains insensitive to changes in carrier concentration. The activation energies of excess carrier generation and removal are estimated from the analysis of the thermal and temporal behaviours of radiation damage in the annealing process. (Author)