Density of States in Intrinsic and n/p-Doped Hydrogenated Amorphous and Microcrystalline Silicon

Larbi F., Belfedal Abdelkader, Sib J. D., Bouizem Y., Chahed L., Amaral A.

.

DOI: 10.4236/jmp.2011.29124                

Abstract

Gap states in amorphous hydrogenated silicon (a-Si:H) doped and microcrystalline silicon doped n and p were examined by analysis of subgap absorption spectra obtained by the Constant Photocurrent Method (CPM) and the Photothermal Deflection Spectroscopy (PDS). Assuming a Gaussian distribution of defect states in the gap, broad distribution of states was found in a-Si:H and doped a-Si:H. A dependence of the defect concentration on Fermi energy was detected and analysed by thermodynamic model of defect formation in a-Si:H.

Keywords

Defects Formation, Doping, Microcrystalline Silicon, Thermodynamic Model of Defect, Optical Properties and Measurements

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	A. Matsuda, “Growth Mechanism of Microcrystalline Silicon Obtained from Reactive Plasma,” Thin Solid Films, Vol. 337, No. 1-2, 1999, pp. 1-6. doi:10.1016/S0040-6090(98)01165-1
[2]	S. K. Ram, S. Kumar and P. R. Cabarrocas, “Role of Microstructure on Electronic Transport Behavior of Highly Crystallized Undoped Microcrystalline Si Films,” Thin Solid Films, Vol. 515, 2007, pp. 7576-7580. doi:10.1016/j.tsf.2007.01.018
[3]	S. K. Ram, S. Kumar and P. R. Cabarrocas, “Model Cal- Culation of Phototransport Properties of Minority Carriers of Fully Crystalline Undoped μc-Si:H,” Thin Solid Films, Vol. 517, No. 23, 2009, pp. 1-4. doi:10.1016/j.tsf.2009.02.110
[4]	M. Stutzmann, “The Defect Density in Amorphous Sili-con,” Philosophical Magazine B, Vol. 60, No. 4, 1989, pp. 5310-5460. doi:10.1080/13642818908205926
[5]	M. Stutzmann, “Weak Bond-Dangling Bond Conversion in Amorphous Silicon,” Philosophical Magazine B, Vol. 56, No. 1, 1987, pp. 63-70. doi:10.1080/13642818708211224
[6]	M. J. Powell and S. C. Deane, “Improved Defect-Pool Model for Charged Defects in Amorphous Silicon,” Physical Review B, Vol. 48, No. 15, 1993, pp. 10815- 10827. doi:10.1103/PhysRevB.48.10815
[7]	K. Wener, “Defect Formation in a-Si:H,” Physical Review B, Vol. 41, No. 17, 1990, pp. 12150-12161.
[8]	R. A. Street and K. Winer, “Defect Equilibria in Undoped a-Si:H,” Physical Review B, Vol. 40, No. 9, 1989, pp. 6236-6249. doi:10.1103/PhysRevB.40.6236
[9]	A. E. Wetsel, S. J. Jones, W. A Turner, D. Pang, W. Paul, I. El Zawawi, Y. Bouizem, L. Chahed, M. L. Thèye, F. C. Marques and I. Chambouleyron, “Structural Properties of Amorphous Germanium,” Materials Research Society Symposium Proceedings, Vol. 192, 1991, pp. 547-551.
[10]	N. M. Amer and W. B. Jackson, “Hydrogenated Amor- phous Silicon,” Semiconductors and Semimetals, Vol. 21B, 1984, pp. 83-88.
[11]	W. Shelter, W. Hell, R. Helbig and M. Schulz, “Optical Properties of Indium-Doped Silicon,” Journal of Physics C: Solid State Physics, Vol. 15, No. 28, 1982, pp. 5839-5844. doi:10.1088/0022-3719/15/28/016
[12]	K. Pierz, B. Hilgenberg, H. Mell and G. Weiser, “Corre-lation between Defect Density and Femi-Level Position in a-Si: H,” Journal of Non-Crystalline Solids, Vol. 97-98, 1987, pp. 91-96.
[13]	S. Yamasaki, H. Okushi, A. Matsuda, H. Oheda, N. Hata and K. Tanaka, “Thickness and Doping Dependance of Optical Gap in Hydrogenated Amorphous Silicon,” Japanese Journal of Applied Physics, Vol. 20, 1981, pp. 655-660.
[14]	K. Pierz, W. Fuhs and H. Mell, Proceedings of the 19th International Conference on the Physics of Semiconduc-tors, PIOP, Warsaw, 1989, pp. 1609-1614.
[15]	N. W. Wang and S. Wagner, American Institute of Physics Conference Proceedings, Vol. 234, 1991, p. 186.
[16]	J. Tauc and A. Menth, “State in the Gap,” Journal of Non-Crystalline Solids, Vol. 8-10, 1972, pp. 569-585. doi:10.1016/0022-3093(72)90194-9
[17]	Y. Bouizem, A. Befedal, J. D. Sib and L. Chahed, “Density of State in Hydrogenated Amorphous Germanium Seen via Optical Absorption Speectra,” Solid State Communi- cations, Vol. 126, No. 12, 2003, pp. 675-680. doi:10.1016/S0038-1098(03)00271-0
[18]	M. Vanecek, A. Abraham, O. Stika, J. Stuchlik and J. Kocka, “The Density of States in Undoped and Doped Hydrogenated Amorphous Silicon,” Physica Status Solidi (A), Vol. 90, No. 1-3, 1987, pp. 9198.
[19]	A. Triska, J. Kocka and M. Vanecek, “Disordered Semi-conuctors,” In: M. A. Kastner, G. A. Thomas and S. R. Ovshinsky, Eds., Plenum, New York, 1987, pp. 459- 465.
[20]	T. Watanabe, K. Azuma, M. Nakatani and T. Shimada, “Gap State in a-SiGe:H Examined by the Constant Photo- Courrent Method,” Japanese Journal of Applied Physics, Vol. 29, 1990, pp. 1419-1425. doi:10.1143/JJAP.29.1419
[21]	R. A. Street, “Hydrogenated Amorphous Silicon,” Cam- bridge University Press, Cambridge, 1991.