Overcoming the doping limit in semiconductors via illumination

It has been shown that illumination could have significant effects on the dopability in semiconductors. However, a general understanding on these effects is still lacking. In this paper, we present a self-consistent scheme to study the doping properties in semiconductors under illumination, and unravel a general picture: the excess carriers induced by illumination can substantially suppress the formation of compensating defects and enhance the carrier mobility as well as the density of the majority carrier, because the illumination leads to an asymmetric Fermi level shift. This is exemplified by a prototype Mg doped GaN system upon exposure to light and is consistent with available experimental observations. Our work provides a fundamental understanding of the physical process occurring in semiconductors upon illumination, and paves the way to overcome the doping bottleneck via nonequilibrium techniques in semiconductors.