Electrical conductivity tuning and valence band splitting studies in Copper Gallium Selenide thin films

Copper gallium selenide (CGS) semiconductor thin films are suitable for various optoelectronic devices due to their stoichiometry dependent properties. Tuning of electrical conductivity (0.5–90 S/cm) by compositional variations of CGS thin films prepared by reactive evaporation of the three elements...

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Bibliographic Details
Published in:Journal of alloys and compounds 2017-12, Vol.729, p.249-256
Main Authors: Abraham, Anitha, Keerthi, K., Shaji, S., Deshpande, Uday, Philip, Rachel Reena
Format: Article
Language:English
Subjects:
Conductivity
Copper
Crystal field theory
Electrical properties
Electrical resistivity
Electron microscopy
Gallium
Hall effect
Optical properties
Optoelectronic devices
Optoelectronics
Reactive evaporation
Scanning electron microscopy
Semiconductors
Spectrum analysis
Studies
Thin films
Tuning
Valence band
Valence band splitting
X ray photoelectron spectroscopy
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Summary:Copper gallium selenide (CGS) semiconductor thin films are suitable for various optoelectronic devices due to their stoichiometry dependent properties. Tuning of electrical conductivity (0.5–90 S/cm) by compositional variations of CGS thin films prepared by reactive evaporation of the three elements under vacuum is presented here. This p-type absorber material withstands its conductivity type over the entire range of compositional variation. The structure, morphology, elemental composition, chemical states, electrical and optical properties of the thin films are characterized using techniques like X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, UV–visible absorption spectroscopy and Hall effect measurements. Optical studies of the films reveal a three-fold absorption from which crystal field splitting ∼0.06 eV and spin orbit splitting ∼0.09–0.17 eV are determined. The optical fundamental absorption edges of the films vary from 1.6 to 1.67 eV. •CGS films well characterized by XRD, Raman, XPS, EDAX and SEM.•Grouping done based on anion/cation ratio for conductivity changes with composition.•Crystal field and spin orbit splitting parameters from optical absorption data.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2017.09.176