Capacitance study of defects induced in heavily damaged region formed in hydrogen implanted Si

Capacitance–voltage (C–V) characteristics at high frequency (1 MHz) as a function of temperature (T) were measured to study defects created by hydrogen implantation followed by high temperature annealing. The initial material used in this study was p-type Czochralski Si (Cz-Si) implanted with 130 keV H2+ at a high dose of 4×1016 cm−2. The post-implantation annealing was carried out in argon ambient at 450 °C per 10 h, i.e. at the temperature of thermal donor creating in Si. The presence of the deep-level defects manifest themselves through several unusual features in C–V(T) characteristics. A flat region, sudden jump of capacitance and hysteresis effect in C–V data were observed during sweeping bias voltage. Our experiments by filling and emptying deep-level defects with carriers before the voltage sweep also revealed unusual hysteresis effects in C–V curves. The results obtained can be readily understood if we assume that deep-level defects in the depletion region are present in very high concentration, the defect spatial distribution is inhomogeneous as usual in implanted samples, and the defects control the electrical characteristics. We also conclude that a relatively thick p-type layer is formed during implantation at the surface of the n-type Si that is formed as a result of annealing.