Impact of the activation of carbon vacancies at high temperatures on the minority carrier lifetimes in the intrinsic area of 4H-SiC PiN rectifier

The temperature dependent behaviour of a high power 4H-SiC PiN-diode was investigated by the adjustment of measured forward characteristics and quasistatic TCAD simulations in a temperature range from RT up to 773 K. The systematic analysis of the relevant physical parameters for the adjustment of measurements and simulations shows, that the predominating influence originates from the SRH (Shockley-Read-Hall) minority carrier lifetimes in the intrinsic region. The carrier lifetimes exhibit a negative temperature coefficient for temperatures above 673 K that disagrees with the theoretical models of the temperature dependence of the SRH recombination caused by just one effective type of impurity. The EH6/7 centers are the most promising candidates for additional recombination centers that become activated at higher temperatures and cause an increase in non-radiative carrier recombination that leads to decreasing SRH carrier lifetime.