Ž . Journal of Non-Crystalline Solids 227–230 1998 254–258 Hydrogenated amorphous silicon deposited by glow discharge of SiH diluted with He: photoluminescence and 4 electroluminescence in the visible region K. Luterova a,b, ) , P. Knapek a , J. Stuchlık a , J. Kocka a , A. Poruba c , J. Kudrna d , ´ ´ ´ ˇ P. Maly d , J. Valenta d , J. Dian d , B. Honerlage b , I. Pelant a ´ ¨ a Institute of Physics, Academy of Sciences of the Czech Republic, CukroÕarnicka 10, 162 00 Praha 6, Czech Republic ´ b IPCMS, Groupe d’Optique Nonlineaire et d’Optoelectronique, Unite Mixte 380064, CNRS-ULP-EHICS, 67037 Strasbourg Cedex, France ´ ´ ´ c Faculty of Chemistry, Technical UniÕersity, Veslarska 230, 637 00 Brno, Czech Republic ˇ ´ d Faculty of Mathematics and Physics, Charles UniÕersity, Ke KarloÕu 3, 121 16 Praha 2, Czech Republic Abstract Ž . Samples of a-Si:H having a wide gap G2.1 eV were prepared using routine rf glow discharge decomposition of silane Ž . SiH strongly diluted with He. Also, microwave electron–cyclotron–resonance plasma-enhanced chemical-vapour-deposi- 4 tion was used to prepare wide-gap a-Si:H via decomposition of He diluted SiH . The wide-gap a-Si:H samples, containing 4 above 30 at.% of hydrogen, exhibit visible photoluminescence at room temperature. From the temperature dependence of photoluminescence intensity and from the observed shift of the maximum with temperature we deduce that the customary model of radiative recombination of carriers localised in tail states is not directly applicable to the case of wide-gap a-Si:H. Ž . Instead, we propose that the photoluminescence arises in parallel from tail states and from isolated extrinsic centres. Electroluminescence results obtained on a p – i – n structure with wide-gap a-Si:H are reported. q 1998 Elsevier Science B.V. All rights reserved. Keywords: a-Si:H; He diluted SiH ; MW ECR PECVD 4 1. Introduction Referring to the current search for Si-based light- Ž wx. emitting materials for a review, see e.g. Ref. 1 , it is evident that the potential for applications of a-Si:H would increase provided this material exhibited visi- Ž . ble photoluminescence PL at room temperature. ‘Standard’ a-Si:H has, however, basically only low- ) Corresponding author. Tel.: q420-2 2431 1137, ext. 414; fax: q420-2 312 3184; e-mail: luterova@fzu.cz. temperature PL in the near infrared region, due to its Ž . wx relatively small optical band gap ; 1.8 eV 2. It is known that increase of hydrogen content in a-Si:H leads to widening of the band gap and in- Ž wx. creases PL quantum efficiency e.g. Ref. 3 . PL peak energy undergoes in this case a blue shift and efficient visible PL, persisting even to room tempera- ture, can appear. To prepare such efficiently luminescing wide-gap a-Si:H, a non-standard preparation process such as homogeneous chemical vapour deposition along with substrate temperatures ; 258C during deposition 0022-3093r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. Ž . PII: S0022-3093 98 00063-5