Influence of sublayer thickness on electroluminescence from a-Si:H/SiNx superlattice structures

Luminescent a-Si:H/SiNx superlattice structures (SLs) with different thicknesses of sublayers were fabricated on indium tin oxide coated glass by three electrode chemical vapour deposition chamber. Transmission electron micrograph revealed small amount of silicon nanocrystallites embedded between two SiNx sublayers. Electroluminescence (EL) and electrical properties of the SLs were investigated. The dominant current mechanism is considered to be Fowler-Nordheim tunnelling under high electric field. EL mechanism is attributed to bipolar recombination of hole-electron pairs. EL spectrum of the SLs was deconvoluted into two Gaussian peaks with a major band at around ~ 700 nm and minor at ~ 560 nm. EL spectra blue-shift with decreasing the thickness of a-Si:H sublayers.