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

Amorphous hydrogenated silicon nitride ®lms (a-Si1ÿxNx:H) can have varied applications in optoelectronics when produced as alloys with a wide range mobility gap. Employing ArF LCVD and using SiH4/NH3 or Si2H6/NH3 as the precursor gases, we have tailored the bandgap (Eg) of this material from 1.6 to 4.9 eV. It was found that Si2H6/NH3 mixture produced highly silicon-rich alloys with compositions below the percolation threshold (x 0:52) of Si±Si bonds and Eg between 1.6 and 2.9 eV, while SiH4/NH3, produced nitrogen-rich alloys (x 0:59) with Eg upto 4.9 eV. This alloy can thus serve as dielectric and passivating ®lms and also as a wide bandgap semiconductor. Correlations of the gap variation with ®lm structure and composition are discussed. # 2000 Elsevier Science B.V. All rights reserved