HYDROGENATED AMORPHOUS-SILICON DEPOSITED BY GLOW-DISCHARGE OF SIH4 DILUTED WITH HE - PHOTOLUMINESCENCE AND ELECTROLUMINESCENCE IN THE VISIBLE REGION

Samples of a-Si:H having a wide gap (greater than or equal to 2.1 eV) were prepared using routine rf glow discharge decomposition of silane (SiH4) strongly diluted with He. Also, microwave electron-cyclotron-re sonance plasma-enhanced chemical-vapour-deposition was used to prepare wide-gap a-Si:H via decomposition of He diluted SiH4. The wide-gap a- Si:H samples, containing above 30 at.% of hydrogen, exhibit visible ph otoluminescence at room temperature. From the temperature dependence o f photoluminescence intensity and from the observed shift of the maxim um with temperature we deduce that the customary model of radiative re combination of carriers localised in tail states is not directly appli cable to the case of wide-gap a-Si:H. Instead, we propose that the pho toluminescense arises in parallel from tail states and from isolated ( extrinsic) centres, Electroluminescence results obtained on a p-i-n st ructure with wide-gap a-Si:H are reported. (C) 1998 Elsevier Science B .V. All rights reserved.