Determination and observation of electronic defect levels in CuInSe sub 2 crystals and thin films

Journal Article · Wed May 01 04:00:00 EDT 1991 · Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA)

DOI:https://doi.org/10.1116/1.577408· OSTI ID:5824633

Abou-Elfotouh, F A; Kazmerski, L L; Moutinho, H R; Wissel, J M; Dhere, R G; Nelson, A J; Bakry, A M ^[1]

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1. Solar Energy Research Institute, Golden, Colorado 80401 (US)

The effects of heat and surface treatments used in the fabrication of CuInSe{sub 2} (CIS) single-crystal and thin-film solar cells are investigated, and the associated dominant defect states are identified using high-resolution photoluminescence (PL) and deep-level transient spectroscopy (DLTS) measurements. The results are correlated with junction electrical characteristics, and comparisons between thin films and single crystals are established. For the first time, direct evidence for several major defect types (Cu vacancies, Cu at In sites, and In at Cu sites) responsible for the majority-carrier type of the CIS is presented based upon spectroscopic atomic imaging of the {ital n}- and {ital p}-type semiconductor surfaces. Radiative recombination levels of extrinsic origin resulting from the surface processing (including polishing, etching, and annealing) were detected in the near surface region of the CIS single crystals, but not in the thin-film material having the same composition. The energy locations and depth of these states are responsible for the formation of an interfacial layer that is confirmed from frequency-dependent capacitance--voltage ({ital C}--{ital V}) data. The DLTS measurements on single-crystal and thin-film heterostructure {l brace}i.e., (Cd,Zn)S/CIS{r brace} devices (of nearly identical chemical compositions) have also confirmed the presence of a dominant trap level in the 270-meV region above the valance band. However, the trap density is some two orders of magnitude lower in the thin-film device, giving evidence that this processing-related defect level is responsible for the inferior performance of the single-crystal solar cells.

• OSTI ID: 5824633
• Journal Information: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA), Journal Name: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA) Vol. 9:3; ISSN JVTAD; ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
COPPER SELENIDE SOLAR CELLS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
CRYSTALS
DIRECT ENERGY CONVERTERS
ENERGY LEVELS
EQUIPMENT
FILMS
HEAT TREATMENTS
INDIUM SELENIDE SOLAR CELLS
LUMINESCENCE
MONOCRYSTALS
PHOTOELECTRIC CELLS
PHOTOLUMINESCENCE
PHOTOVOLTAIC CELLS
RECOMBINATION
SOLAR CELLS
SOLAR EQUIPMENT
SURFACE TREATMENTS
THIN FILMS