Electrical properties of selenium-diffused silicon

The energy levels of selenium in silicon have been measured by fitting the theoretical carrier concentration versus temperature equation for semiconductors containing both double donors and acceptors to the experimental curve obtained from the Hall coefficient. The resistivity and Hall coefficient were measured by the van der Pauw method for samples diffused at 1100–1200°C for 68–168 hours. Selenium in silicon is a double donor impurity with energy levels of 0.26 and 0.50 eV below the conduction band edge. The ratios of the state degeneracies of neutral and singly ionized selenium centers, γ₁, and of singly and doubly ionized selenium centers, γ₂, are found to be 1/2 and 2 respectively. Selenium in silicon may be thought of as the analogue of a helium-like center in silicon.