Conversion of Direct to Indirect Bandgap and Optical Response of B Substituted InN for Novel Optical Devices Applications

Optical properties of B_xIn_{1 - x}N are calculated as a function of the varying concentration of boron and indium. Indium is gradually replaced by boron and optical properties of the resulting materials are studied. The fractional concentration of boron is increased gradually from x = 0 to x = 1 in steps of 0.25. The bandgap increases with the increasing boron concentration, from 0.95 eV for pure InN to 5.6 eV for BN. A unique behavior of BN in zinc-blend phase is observed, that is, it shifts from indirect to direct bandgap semiconductor by the substitution of In on B sites. This behavior can be used to make novel and advanced optical devices. Frequency dependent reflectivity, absorption coefficient, and optical conductivity of B_xIn_{1 - x}N are calculated and found to be the constituent´s concentration dependent. The region of reflectivity, absorption coefficient and optical conductivity shifts from lower frequency into the higher frequency as the material goes from pure InN to pure BN.