We present first-principles calculations of the band-gap properties of the zinc-blende BN, GaN and B<sub>x</sub>Ga<sub>1-x</sub>N alloys. By
16-atom supercells to model a random alloy, the direct band-gap (Γ<sub>15v</sub>-Γ<sub>1c</sub>) bowing of 5.0 eV is obtained for B<sub>x</sub>Ga<sub>1-x</sub>N
alloys in the range of 0~37.5%, and the bowing parameter increases by 0.043eV/%B with boron (B) composition
increasing. In addition, our calculated results show that 0.8eV (1550nm) direct transition band-gap energy of
B<sub>x</sub>Ga<sub>1-x</sub>N<sub>y</sub>As<sub>1-y</sub> lattice matches to Si can be theoretically obtained while boron (B) composition is 4% and nitrogen (N)
composition is 16%.