Defect induced ambipolar conductivity in wide-bandgap semiconductor SrS: Theoretical perspectives

Abstract

Due to the absence of high-performance ambipolar wide-bandgap (WBG) semiconductors, the realization of active transparent photoelectronic devices is precluded. Herein, based on the hybrid functional calculations, we predict that, in a wide-bandgap semiconductor strontium sulfide (SrS), the Br (Rb) substituting S (Sr) is an ideal n (p)-type defect. SrBr2 and Rb2S are promising dopant sources for introducing Br and Rb, respectively. Moreover, the Sr-rich (Sr-poor) condition is the optimum growth environment to fabricate the BrS (RbSr) defects. Thermodynamic equilibrium simulations indicate that the concentration of BrS and RbSr can exceed 4 × 1019 cm−3 at high growth temperatures. After rapid quenching from the growth temperature to room temperature, the free carrier densities can reach 1.56 × 1019 cm−3 for electrons and 1.02 × 1018 cm−3 for holes. These results show SrS is a promising ambipolar WBG semiconductor that has huge potential applications in future optoelectronic devices.