Electronic structure and improved optical properties of Al, P, and Al-P doped h-BN

The electronic structures and optical properties of pure, Al-doped, P-doped, and AlP co-doped h-BN were studied by the first principle calculation. h-BN is a typical wide direct bandgap semiconductor with 4.88 eV, and its absorption is mainly in the low ultraviolet and short ultraviolet band. After different doping, the bandgap decreases in decreasing order of Al-doped (4.58 eV), AlP ortho co-doped (3.91 eV), AlP para co-doped (3.82 eV), and P-doped (3.67 eV) h-BN. Furthermore, h-BN changes from a direct bandgap semiconductor after Al or P doping, into an indirect bandgap semiconductor. Although the optical absorption peak intensity of all doped systems decreases, the absorption edge exhibits an obvious red shift except for Al-doped h-BN. The largest red shift of the absorption edge is AlP para co-doped h-BN, followed by AlP ortho co-doped h-BN and P-doped h-BN. The smaller band gap of P-doped h-BN than AlP co-doped h-BN has a smaller red shift of the absorption edge, and the slight blue shift of the absorption edge of Al-doped h-BN is due to their changes in semiconductor characteristics (indirect bandgap semiconductor). The red shift of the absorption edge for the doped h-BN greatly expands its application in opto-electron devices.