Hostname: page-component-8448b6f56d-mp689 Total loading time: 0 Render date: 2024-04-24T18:11:10.274Z Has data issue: false hasContentIssue false
  • English
  • Français

Density of States of Amorphous Germanium Thin Films Deposited by the Pecvd of H2-Diluted Germane

Published online by Cambridge University Press:  25 February 2011

C. Godet ,
V. Chu ,
B. Equer ,
Y. Bouizem ,
L. Chahed ,
I. El Zawawi ,
M. L. Theye ,
S. Basrour ,
J. C. Bruyere  and
J.P. Stoquert
C. Godet
Affiliation:
Laboratoire de Physique des Interfaces et des Couches Minces, UPR A 0258 - CNRS, Ecole Polytechnique - 91128 Palaiseau-Cedex, (France).
V. Chu
Affiliation:
Laboratoire de Physique des Interfaces et des Couches Minces, UPR A 0258 - CNRS, Ecole Polytechnique - 91128 Palaiseau-Cedex, (France).
B. Equer
Affiliation:
Laboratoire de Physique des Interfaces et des Couches Minces, UPR A 0258 - CNRS, Ecole Polytechnique - 91128 Palaiseau-Cedex, (France).
Y. Bouizem
Affiliation:
Laboratoire d’Optique des Solides, URA CNRS 781, Université P. et M. Curie, 4 place Jussieu, 75252 Paris-Cedex 05, (France).
L. Chahed
Affiliation:
Laboratoire d’Optique des Solides, URA CNRS 781, Université P. et M. Curie, 4 place Jussieu, 75252 Paris-Cedex 05, (France).
I. El Zawawi
Affiliation:
Laboratoire d’Optique des Solides, URA CNRS 781, Université P. et M. Curie, 4 place Jussieu, 75252 Paris-Cedex 05, (France).
M. L. Theye
Affiliation:
Laboratoire d’Optique des Solides, URA CNRS 781, Université P. et M. Curie, 4 place Jussieu, 75252 Paris-Cedex 05, (France).
S. Basrour
Affiliation:
Laboratoire d’Etude des Propriétés Electroniques des Solides, CNRS, , BP 166X, 38042 Grenoble-Cedex, (France).
J. C. Bruyere
Affiliation:
Laboratoire d’Etude des Propriétés Electroniques des Solides, CNRS, , BP 166X, 38042 Grenoble-Cedex, (France).
J.P. Stoquert
Affiliation:
Laboratoire PHASE, Centre de Recherches Nucleaires, BP 20, 67037 Strasbourg, (France).
Get access

Abstract

The disorder in a-Ge:H thin films produced by the plasma-enhanced chemical vapor deposition (PECVD) technique is strongly reduced when the GeH4 gas is diluted at 1% in H2 and the radiofrequency power density is increased to 0.1 W.cm−2. This improvement is attributed to a better surface passivation by the hydrogen atoms during the growth. However, the poor transport properties indicate a still high defect density. The midgap defect absorption and the Urbach energy, obtained from the photothermal deflection spectra calibrated with optical data, both decrease as a function of the film thickness. The optical defect density is calibrated with EPR spin measurements. For a-Ge:H films thicker than 2 μm, obtained at a deposition temperature Ts ranging from 150 to 250°C, the Urbach tail parameter E° is lower than 50 meV and not sensitive to Ts ; the dangling bond density is around 4.107 cm−3, which is higher by a factor of 100 than in a-Si:H. Preliminary transport measurements indicate that the Fermi level density of states is larger than 1018 cm−3.eV−1.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 192: Symposium O – Amorphous Silicon Technology - 1990 , 1990 , 163
Copyright
Copyright © Materials Research Society 1990

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Stutzmann, M., Street, R.A., Tsai, C.C., Boyce, J.B. and Ready, S.E., J. Appl. Phys. 66 (2), 569 (1989).Google Scholar
Godet, C., El Zawawi, I., Thèye, M.L., Gauthier, M. and Stoquert, J.P., Solid State Commun. (1990) to be published.Google Scholar
The positive ion flux, measured in a replica of the ‘ARCAM’ deposition set-up in the configuration “A”, increases in the range 0.8 to 1.5 103 ions.cm−2, when the flow-rate ratio [GeH4½ / [GeH4 + H2] decreases from 0.20 to 0.01, at a power density W = 0.05 W.cm−2. The typical ion energy is 25 eV.Google Scholar
Ref: Drévillon, B., Godet, C. and Antoine, A., Mat. Res. Soc. Symp. Proc. (Pittsburgh, 1987) edited by Donnelly, V.M., Herman, LP. and Hirose, M., 75 341 (1987).Google Scholar
Matsuda, A. and Tanaka, K., J. Non-Crystal. Solids 97 & 98 1367 (1987).Google Scholar
[5] Roca, P. Cabarrocas, i, Equer, B., Hue, J., Lloret, A. and Schmitt, J.P.M., 7th E.C. Photovoltaic Solar Energy Conf. (Sevilla, 1986) edited by Goetzberger, A., Palz, W. and Willeke, G. (D. Reidel, Dordrecht, 1986) p. 533.Google Scholar
[6] Chahed, L., Gheorghiu, A., Thèye, M.L., Ardelean, I., Sénémaud, C. and Godet, C., 13th Int. Conf. Amorphous and Liquid Semiconductors (Asheville, 1989).Google Scholar
J. Non-Cryst. Solids 114 762 (1989).Google Scholar
[7] Kocka, J., Vanecek, M. and Triska, A., in Amorphous Silicon and related materials. Vol. A, edited by Fritzsche, H. (World Scientific, Singapore, 1989) pp.297–327.Google Scholar
[8] Jackson, W.B. and Amer, N.M., Phys. Rev. B 25. (8) 5559 (1982).Google Scholar
Skumanich, A. and Amer, N.M., J. Non-Crystal. Solids 59 & 60 249 (1983).Google Scholar
[9] Nobile, G. and McMahon, T.J., J. Appl. Phys. 67 (1) 578 (1990).Google Scholar
[10] Curtins, H. and Favre, M., in Amorphous Silicon and related materials. Vol. A, edited by Fritzsche, H. (World Scientific, Singapore, 1989) pp. 329–363.Google Scholar
[11] Bustarret, E., private communication.Google Scholar
[12] Fang, C.J., Gruntz, K.J., Ley, L., Cardona, M., Demond, F.J., Müller, G. and Kalbitzer, S., J. Non-Cryst. Solids 35 & 36 255 (1980).Google Scholar
[13] Reimer, J.A., Scott, B.A., Wolford, D.J. and Nijs, J., Appl. Phys. Lett. 46 (4) 369 (1985).Google Scholar
[14] Godet, C., Bouizem, Y., Chahed, L., El Zawawi, I., Thèye, M.L., Basrour, S., Bruyère, J.C. and Meaudre, R.. Submitted to Phys. Rev. LettGoogle Scholar