Photo-induced deposition and characterization of variable bandgap a-SiN:H alloy films

Abstract Amorphous hydrogenated silicon nitride films (a-Si 1− x N x :H) can have varied applications in optoelectronics when produced as alloys with a wide range mobility gap. Employing ArF LCVD and using SiH 4 /NH 3 or Si 2 H 6 /NH 3 as the precursor gases, we have tailored the bandgap ( E g ) of this material from 1.6 to 4.9 eV. It was found that Si 2 H 6 /NH 3 mixture produced highly silicon-rich alloys with compositions below the percolation threshold ( x ∼0.52) of Si–Si bonds and E g between 1.6 and 2.9 eV, while SiH 4 /NH 3 , produced nitrogen-rich alloys ( x ∼0.59) with E g upto 4.9 eV. This alloy can thus serve as dielectric and passivating films and also as a wide bandgap semiconductor. Correlations of the gap variation with film structure and composition are discussed.