Absorption and the optical gap of a-C:H films produced from acetylene plasmas
Tóm tắt
Films of amorphous hydrogenized carbon (a-C:H) are prepared by chemical vapor deposition using a dc glow discharge. The absorption is studied over wavelengths of 400–2400 nm. Two Gaussian-like bands are identified with peaks at ∼600 and ∼800 nm. The ratio of the integrated intensities of these bands (I
600/I
800) is found to decrease as the voltage is raised. The changes in the ratio I
600/I
800 are compared with the variation in the fundamental Raman scattering bands in order to clarify the nature of the visible absorption in the a-C:H films. Two simple schemes for transparent insulating films with E
T
⩾1.5 eV and for “black” conducting a-C:H films with E
T
⩽1 eV are proposed for explaining the relationship between the structure of the absorption edge and the width of the Tauc gap (E
T
).
Tài liệu tham khảo
J. Robertson, Thin Solid Films 296, 61 (1997).
B. S. Satyanarayana, A. Hat, and W. I. Milne, J. Robertson, Appl. Phys. Lett. 71(10), 1430 (1997).
S. Egret, J. Robertson, W. I. Milne, and F. J. Clough, D & RM 6, 879 (1997).
B. Singh, S. McClelland, F. Tams III, B. Halon, O. Mesker, and D. Furst, Appl. Phys. Lett. 57, 2288 (1990).
E. A. Konshina and A. P. Onokhov, Zh. Tekh. Fiz. 69(3) (1999) [sic].
I. Wanatabe, S. Hasegawa, and Y. Kurata, Jpn. J. Appl. Phys. 22, 856 (1982).
D. I. Jones and A. D. Stewart, Philos. Mag. B 246, 423 (1982).
E. Pascual, C. Serra, J. Esteve, and E. Bertran, Surf. Coat. Technol. 247, 263 (1991).
Fangoing Zhang, Guanch Chen, Yafei Zhang, and Gong Yu, Phys. Status Solidi A 109, K39 (1988).
A. Bubenzer, B. Dischler, G. Branat, and P. Koidl, J. Appl. Phys. 54, 4590 (1983).
K. Yamamoto, Y. Ichikawa, T. Nakayama, and Y. Tawada, Jpn. J. Appl. Phys. 27, 1415 (1988).
C. Serra, E. Pascual, F. Maass, and J. Esteve, Surf. Coat. Technol. 247, 87 (1991).
K. Rohwer, P. Hammer, J.-U. Thiele, W. Gissler, P. Blaudeck, T. Frauenheim, and D. Meissner, J. Non-Cryst. Solids 137–138, 843 (1991).
E. A. Konshina, Fiz. Tverd. Tela 37, 1120 (1995) [Phys. Solid State 37, 610 (1995)].
A. V. Balakov and E. A. Konshina, Zh. Tekh. Fiz. 52, 808 (1982) [Sov. Phys. Tech. Phys. 27, 520 (1982)].
J. Tauc, R. Grigorovici, and A. Vancu, Phys. Status Solidi 15, 627 (1966).
J. Robertson, Adv. Phys. 35, 317 (1986).
J. Robertson and E. P. O’Reilly, Phys. Rev. B 35, 2946 (1987).
J. Robertson, Surf. Coat. Technol. 50, 185 (1992).
J. Robertson, D & RM 6, 212 (1997).
Th. Frainheim, P. Blaudeck, U. Stephan, and G. Jungnickel, Phys. Rev. B 48, 4823 (1993).
G. Jungnickel, Th. Frainheim, D. Porezag, P. Blaudeck, U. Stephan, and R. J. Newport, Phys. Rev. B 50, 6709 (1994).
R. O. Dillon, J. A. Woollam, and B. Katkanant, Phys. Rev. B 29, 3482 (1984).
M. Ramsteiner and J. Wagne, Appl. Phys. Lett. 51, 1355 (1987).
M. Yoshikawa, G. Katagiri, H. Ishida, A. Ishitani, and T. Akamatsu, Appl. Phys. Lett. 52, 1639 (1988).
M. A. Tamor, J. A. Haire, C. H. Wu, and K. C. Hass, Appl. Phys. Lett. 54, 123 (1989).
A. V. Baranov and E. A. Konshina, Opt. Spektrosk. 65, 856 (1988).
E. A. Konshina and A. V. Baranov, Poverkhnost’, No. 4, p. 53 (1989).
J. K. Walters, P. Honeybon, D. W. Huxley, and R. J. Newport, Phys. Rev. B 50, 831 (1994).
M. Jager, J. Gottward, H. W. Spiess, and R. J. Newport, Phys. Rev. B 50, 848 (1994).
J. R. Honeybone, R. J. Newport, J. K. Walters, W. S. Howells, and J. Tomkinson, Phys. Rev. B 50, 839 (1994).
Satoshi Matsunuma, Thin Solid Films 306, 17 (1997).
S. Xu, M. Hundhausen, J. Ristein, B. Xan, and L. Le, J. Non-Cryst. Solids 164–166, 1127 (1993).
E. A. Konshina, A. V. Baranov, and V. B. Yakovlev, Zh. Prikl. Spektrosk. 48, 957 (1988).
O. V. Sverdlova, in Electronic Spectra in Organic Chemistry [in Russian], Khimiya, Moscow (1985), p. 121.
D. Dasgupta, F. Demichelis, C. F. Pirri, and A. Tagliaferro, Phys. Rev. B 43, 2131 (1991).
D. Dasgupta, C. De Martino, F. Demichelis, and A. Tagliaferro, J. Non-Cryst. Solids 164–166, 1147 (1993).