InP air/semiconductor gratings formed by the wafer fusion technique is investigated for implementation in novel structures. The grating shape after wafer fusion is changed depending on the duty cycle and/or the fused temperature. The cross-sectional view of the fused interface, observed using transmission electron microscopy (TEM), shows that there is no threading dislocation and the fused interface is not flat but curved, due to the mass-transport phenomenon. We also find that no voltage barrier exists at the n-n fused interface, but a voltage barrier exists at the p-p fused interface. The mass-transport has a significant influence on the electrical characteristics of the fused interface. A single longitudinal mode oscillation of a distributed feedback (DFB) laser with air/semiconductor gratings embedded by wafer fusion technique is demonstrated under pulsed Condition at room temperature. The lasing wavelength is about 1.28 mu m. The threshold current is 180 mA and the threshold current density is estimated to be about 1.3 kA/cm(2).