AMORPHOUS HYDROGENATED SILICON-NITRIDE DEPOSITED BY MERCURY PHOTOSENSITIZATION CHEMICAL-VAPOR-DEPOSITION FOR OPTOELECTRONIC APPLICATIONS

In this work we focus on the properties of amorphous hydrogenated sili con nitride (a-SiN:H) films deposited by mercury sensitization Photo-C hemical Vapour Deposition (Photo-CVD) utilizing SiH4 and NH3 and their suitability for the realization of III-V semiconductor optoelectronic devices (dielectric insulation, protection of reverse junctions, proc ess mask, selective regrowth, antireflection coating). Using proper de position conditions we have obtained a-SiN:H films with breakdown fiel d of 8.9 MV/cm, good spatial uniformity of the dielectric properties, refractive index of 1.85 at 1535 nm, quasi-stoichiometric composition (Si/N=0.8), energy gap of 4.22 eV and density of 2.51 g/cm(3), absence of pores and bubbles. We can reproduce film thickness, refractive ind ex and energy gap within +/-3%, +/-0.005 and 0.05 eV respectively. SiN /InP structures similar to the actual optoelectronic devices have been employed in order to test mechanical adhesion and thickness of the a- SiN:H film grown on vertical facets. A-SiN:H films deposited in the op timized conditions have been successfully used in the previously menti oned applications.