Abstract
Using transient capacitance and transient spin techniques, we have the determined the manner in which the mobility gap energy of the D defect is altered following a change in its charge state. This relaxation process gives rise to a power law rather an exponential thermal release of defect electrons with time and also causes the charge emission and spin transients to obey a scaling law. We also deduce that the D°/D+ transition rate depends on the tenure of the proceeding D−/D° transition. This last aspect of the D defect emission behavior implies that it must be treated as a non-Markovian process. Such relaxation dynamics have profound consequences for the steady state distribution of D defect energies. Using the relaxation parameters determined by the transient measurements we have been able to solve a set of coupled differential equations under steady-state conditions to provide the energy distributions of both the D° and D− defect sub-bands. The results of these calculations agree remarkably well with the experimental distributions determined by modulated photocurrent and steady-state capacitance measurements. This implies that the statistical variations in the occupation history of the defect may be the dominant factor determining both distributions.
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References
D. V. Lang, J. D. Cohen, and J. P. Harbison, Phys. Rev. B25 5285 (1982).
N. M. Amer and W. Jackson, in Semiconductors and Semimetals, ed. by J. Pankove (Academic, New York, 1984), Vol. 21B, p. 83.
See, e.g., P.G. LeComber and W.E. Spear, Philos. Mag. Lett. 53, L1 (1986).
Y. Bar-Yam and J.D. Joannopoulos, Phys. Rev. Lett. 56, 2203 (1986).
S. C. Deane and M. J. Powell, Phys. Rev. Lett. 70, 1654 (1993).
H. M. Branz, Phys. Rev. B39 5107 (1989).
T. M. Leen, and J. D. Cohen, J. Non-Cryst. Solids 137&138, 319 (1991).
J. D. Cohen, T. M. Leen, and R. J. Rasmussen, Phys. Rev. Lett. 69, 3358 (1992).
We exposed samples to 1.9 eV light at 400 mW/cm2 at 300K for ≥ 20 hours.
T. M. Leen, J. D. Cohen, and A. V. Gelatos, Mat. Res. Soc. Symp. Proc. 192, 707 (1990).
H. Okushi, N. Orita, K. Arai, and K. Tanaka, J. Non-Cryst. Solids 137&138, 175 (1991).
R. J. Rasmussen, J. D. Cohen, and J. M. Essick, Mat. Res. Soc. Symp. Proc. 219, 569 (1991).
H. Oheda, J. Appl. Phys. 52, 6693 (1981).
G. Schumm and G.H. Bauer, Phys. Rev. B39, 5311 (1989)
F. Zhong and J.D. Cohen, Mat. Res. Soc. Symp. Proc. 258, 813 (1992).
The MPC derived DOS reflect bulk film properties since this is where the photocarriers spend most of their time and thus will most likely suffer phase shifts due to deep trapping.
C. E. Micheleson, A.V. Gelatos, and J.D. Cohen, Appl.Phys Lett. 47, 412 (1985)
K. K. Mahavadi, K. Zellama, and J. D. Cohen, Phys. Rev. B35, 7776 (1987).
R. G. Palmer, D. L. Stein, E. Abrahams, and P. W. Anderson, Phys. Rev. Lett. 53, 958 (1984).
K. Hattori, Y. Niwano, H. Okamoto and Y. Hamakawa, J. Non-Cryst. Solids, 137&138, 363 (1991)
Acknowledgments
We wish to thank Roger Haydock for many useful discussions and suggestions. This work was supported by NSF Grants DMR-8903383 and DMR-9208334.
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Cohen, J.D., Leen, T.M., Zhong, F. et al. Defect Relaxation Dynamics in Amorphous Silicon. MRS Online Proceedings Library 297, 183–194 (1993). https://doi.org/10.1557/PROC-297-183
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DOI: https://doi.org/10.1557/PROC-297-183