Controlled compensation via non-equilibrium electrons in ZnO

Doping wide-band-gap semiconductor with impurities always accompanied spontaneous compensation of opposite charged intrinsic defects, which lead to invalid control of the type of free carriers. We demonstrate an effectual route to overcoming such detrimental defects formation during doping by suppressing Fermi level shifting using non-equilibrium carriers gathering on the polar epitaxial surfaces. Non-equilibrium carriers are generated by ultraviolet light excited interband transitions (photon energy greater than bandgap). Because the p-type dopants are compensated by non-equilibrium electrons at metal-polar surfaces, donor-type native defects are inhibited. This new doping strategy provides an attractive solution to self-compensation problems in wide–band-gap semiconductors with spontaneous polarization of the future.