Deep traps in CdTe induced by ion implantation and annealing

The effects of In and Kr ion implantation and thermal annealing in n-type C dTe have been studied using Schottky barrier capacitance-voltage (C-V) meas urements and deep level transient spectroscopy (DLTS). Using ion energies o f 40-250 keV and doses of 10(13)-10(16) cm(-2), severe lattice damage was f ound in depths between 0.3 and 1.0 mu m. While the damage was largely remov ed by mild annealing under vacuum (45 min at 200 degrees C), such annealing treatment for both implanted and unimplanted samples resulted in the forma tion of a surface layer with reduced effective shallow donor concentration and the creation of trapping states at energy (E-c - 0.15 eV). Both feature s were: (i) enhanced by successive vacuum annealing cycles at temperatures up to 450 degrees C; (ii) suppressed by annealing under Cd vapour, instead of vacuum, thereby indicating that both effects can be attributed tb the pr esence of Cd vacancies. (C) 2000 Elsevier Science Ltd. All rights reserved.