Comparative optical absorption and photoreflectance study of n‐type CuInSe₂ single crystals

Abstract

Optical absorption spectra in the photon energy range from 0.4 to 1.2 eV and photoreflectance spectra in the range of the fundamental edge are measured on n-type CulnSe, single crystals. Photoreflectance spectroscopy yields the true gap energy while the near-edge absorption spectra are dominated by acceptor -to -conduction band transitions, the acceptor ionisation energy being about 80 meV. Based on intrinsic defect chemistry considerations this acceptor is ascribed to copper vacencies.An n-leitenden CuInSe,-Einkristallen wurden optische Absorptionsspektren im Photonenenergiebereich von 0,4 bis 1,2 eV und Photoreflexionsspektren im Bereich der fundamentalen Absorptionskante gemessen. Die Photoreflexionsspektroskopie liefert die wahre Breite der verbotenen Zone, wlhrend die kantennahen Absorptionsspektren durch Akzeptor -Leistungsband -ubergange domjniert werden, wobei die Akzeptorionisierungsenergie etwa 80 meV betriigt. Auf der Grundlage von Uberlegungen 2ur Eigendefektchemie wird dieser Akzeptor Kupfervakanzen zugeschrieben.

Structural and optical properties of thin films of Cu(In,Ga)Se2 semiconductor compounds

“…As the temperature in the experiment is reduced, the fundamental absorption edge shifts toward higher energies, as is typical for straight band CIGS semiconductors. The optical absorption coefficient α(hν) was calculated using the formula [16] …”

Photoacoustic Spectroscopy of Defect States in Etched and Air‐annealed CuInSe2 Single Crystals

“…These compositions correspond to those of 23.0 to 24.0 at.% copper, 26.0 to 27.0 at.% indium and 49.5 to 51.0 at.% selenium of the thin films used in related previous investigations (NOUFI, CAHEN). It has been found that single crystals with compositions in this range can be both p-type and n-type conducting (ZEGADI et al 1992) in dependence on the specific intrinsic defect equilibrium (for a discussion of this point see YAKUSHEV et al 1994~). For the present study we selected n-type conducting samples that are converted to p-type conductivity as the result of annealing in air at sufficiently high temperatures (NOUFI et al 1986(NOUFI et al , 1987.…”

Stimulated Emission and Optical Properties of Solid Solutions of Cu(In,Ga)Se2 Direct Band Gap Semiconductors

“…В области 1.0-1.4 эВ измеренный коэффициент оптического отражения тонких пленок R ~ 0.15. Коэффициент поглощения рассчитан по формуле [22]: На рис. 3 показаны спектры ФЛ необлученной и облученных пленок CIGSe, зарегистрированные при 20 К и низком уровне возбуждения ~3 Вт/см 2 излучением лазера с = 532 нм.…”