Abstract
A comprehensive study of the properties of undoped and iodine-doped CdTe structures by photoluminescence (PL) and photoreflectance (PR) is reported. Undoped bulk CdTe and iodine-doped CdTe layers grown by metalorganic molecular beam epitaxy on (lOO)-oriented CdTe and (211)B-oriented GaAs substrates with electron concentrations ranging from 1014 to mid-1018 cm-3 were included in this study. Lineshape modeling of 80KPL and PR spectra indicated the presence of both free exciton and donor-hole transitions at the higher doping levels. Strong PL and PR signals were also observed at room temperature. If only a single transition is considered for the analysis of the 300K spectra, the PL emission peak and the PR transition energy both exhibit a strong dependence on electron concentration for doped layers. However, lineshape modeling of the room-temperature spectra indicated the presence of multiple transitions consisting of free exciton and direct band-to-band transitions. The use of two transitions resulted in a constant value of bandgap over the entire range of conductivities studied. A strong correlation remained between the broadening of the PR and PL spectra and excess carrier concentration ND-NA. In addition, the E1 transition energy measured by PR was found to vary dramatically with growth conditions.
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References
D. Rajavel and C.J. Summers,Appl. Phys. Lett. 60, 2231 (1992).
D. Rajavel, B.K. Wagner, R.G. Benz II, A. Conte, K. Maruyama, C.J. Summers and J.D. Benson,J. Vac. Sci. Technol. B 10, 1432 (1992).
N.C. Giles, Jaesun Lee, D. Rajavel and C.J. Summers,J. Appl. Physics 73, 4541 (1993).
Zhonghai Yu, M.A. Mattson, T.H. Myers, K.A. Harris, R.W. Yanka, L.M. Mohnkern, L.C. Lew YanVoon, L.R. Ram-Mohan, R.G. Benz II, B.K. Wagner and C.J. Summers,J. Electron. Mater. 24, 687 (1995).
J.M. Francou, K. Saminadayar and J.L. Pautrat,Phys. Rev. B 41, 12035 (1990).
N.C. Giles, Ph.D. Thesis, Physics, North Carolina State University (1987); and N.C. Giles, K.A. Bowers, R.L. Harper, Jr., S. Hwang and J.F. Schetzina,J. Crystal Growth 101, 67 (1990).
A recent review pertinent to confined systems can be found by O.J. Glembocki and B.V. Shanabrook,Semiconductors and Semimetals, vol. 36 (New York: Academic Press, 1992).
D.M. Eagles,J. Phys. Chem. Solids 16, 76 (1960).
Jaesun Lee, N.C. Giles, D. Rajavel and C.J. Summers,Phys. Rev. B 49, 1668 (1994).
A review of radiative emission lineshapes for common luminescence processes can be found in Barry Bebb and E.W. Williams,Semiconductors and Semimetals, vol. 8 (New York: Academic Press, 1972).
C. Vasquez-Lopez, H. Navarro, Raul Aceves, M.C. Vargas and Cornelius A. Menezes,J. Appl. Phys. 58, 2066 (1985).
A conservative variation of Eg with Cd1-xZnxTe composition was obtained using expressions in: D. J. Olego, J.P. Faurie, S. Sivananthan and P.M. Raccah,Appl. Phys. Lett. 47, 1172 (1985); and T.M. Razykov,Thin Solid Films 164,301 (1988).
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Giles, N.C., Lee, J., Myers, T.H. et al. Optical properties of undoped and iodine-doped CdTe. J. Electron. Mater. 24, 691–696 (1995). https://doi.org/10.1007/BF02657980
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DOI: https://doi.org/10.1007/BF02657980