Effect of Deep-Level Defects on Transient Photoconductivity of Semi-Insulating 4H-SiC

A model enabling the equilibrium conductivity and transient photoconductivity of semi-insulating 4H-SiC to be simulated has been demonstrated. Using this model, the simulations of both equilibrium conductivity and transient photoconductivity have been carried out. Both the simulation and experimental results have shown that the evolution of photoconductivity in time after switching on the band-to-band generation of electron-hole pairs is strongly affected by the properties of deep level defects. The results of transient photocurrent measurements confirm the simulations results indicating that the $Z_{1/2}$ center is a very effective recombination center in semi-insulating 4H-SiC having detrimental effect on the transient photoconductivity.