Combined lifetime killing by platinum and fast light ions in silicon power diode : thermal stability of introduced radiation defects
The influence of combined lifetime killing by platinum in-diffusion and fast light ion irradiation on generation and stability of introduced radiation defects was investigated in the low-doped n-type float-zone oxygen rich silicon forming the base of power pnn diodes. Different concentrations of platinum substitutionals were introduced by platinum implantation and subsequent annealing at temperatures ranging from 725 to 900°C. Diodes were then irradiated with 1.8 MeV protons or 5 MeV alphas to fluences ranging from 5x10 to 1x10 cm. The influence of platinum doping on introduction rates of dominant radiation defects and their thermal stability during subsequent isochronal annealing was investigated by deep-level transient spectroscopy. Results show that the presence of platinum atoms significantly influences introduction rates of dominant recombination centers introduced both by hydrogen and helium irradiation (vacancy-oxygen pairs, divacancies and VOH complexes). Simultaneously, temperature stability of vacancy-oxygen pairs and divacancies decreases of up to 150°C. In both cases, these effects are proportional to platinum concentration introduced into diodes.
Effect of high-temperature heat treatment on the generation and annealing of radiation-induced defects in n-type silicon crystals
Defect formation and annealing processes in n-type silicon crystals heat-treated at temperatures from 550 to 1000°C for a short time and then gamma-irradiated in a 60Co source or electron-irradiated (E = 4 MeV) at room temperature have been studied using Hall effect measurements. The results demonstrate that the preheat treatment (PHT) has an insignificant effect on the energy spectrum and generation efficiency of major defect species. At the same time, PHT results in enhanced annealing of radiation-induced defects, accompanied by the formation of additional electrically active centers. PHT is assumed to activate transition-metal impurities (fast diffusers in silicon), which then interact with radiation-induced defects.
Defect distribution near the surface of electron‐irradiated silicon
The surface‐defect distributions of electron‐irradiated n‐type silicon has been investigated using a transient capacitance technique. Schottky, p‐n junction, and MOS structures were used in profiling the defect distributions. Surface depletions of defects observed were attributed to the vacancy distribution but not that of oxygen and other capture center’s distribution. The vacancy diffusion length at 300 °K was estimated to be about 3–6 μm.