High-resolution laser beam induced current measurements on Cd0.9Zn0.1S/ CdTe solar cells

Brooks, William, Irvine, Stuart and Barrioz, Vincent (2011) High-resolution laser beam induced current measurements on Cd0.9Zn0.1S/ CdTe solar cells. Energy Procedia, 10. pp. 232-237. ISSN 1876 6102

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Official URL: http://dx.doi.org/10.1016/j.egypro.2011.10.183

Abstract

An assessment of Cd0.9Zn0.1S window layer thickness and its impact on photoresponse uniformity in CdTe thin film photovoltaic (PV) devices is presented. A triple-wavelength laser beam induced current (LBIC) system provided a spatially resolved photocurrent mapping technique. Three diode lasers; λ = 405, 658, 810 nm gave photon absorption and carrier generation characteristics over the spectral range of the Cd0.9Zn0.1S/ CdTe devices. Two contrasting device structures were grown by metal-organic chemical vapour deposition (MOCVD), where the uniformity of the Cd0.9Zn0.1S window layer was known to vary: 1. uniform 240 nm Cd0.9Zn0.1S/ 2 μm CdTe and 2. a poorly nucleated 40 - 300 nm Cd0.9Zn0.1S/ 2 μm CdTe. Calculated photon penetration depths, δp allowed for the separation of identified defects within the device cross-section. Cd0.9Zn0.1S pin holes were identified in 240 nm Cd0.9Zn0.1S/ 2 μm CdTe where 405 nm photon ‘punch-through’ into the absorber material was observed. These pin holes also led to a localised reduction in photoresponse at λ = 658 and 810 nm. In the device structure where the Cd0.9Zn0.1S window layer thickness was known to vary from 40 to 300 nm, CdTe pin holes were identified where localised ∼ 50 μm regions of reduced photoresponse, at all wavelengths were observed. Local variations in both Cd0.9Zn0.1S and CdTe thickness were also identified where variable absorption led to a distribution of LBIC photoresponse. It was demonstrated that reduced photoresponse uniformity at all incident wavelengths was related to reduced device shunt resistance, Rsh and open-circuit voltage, Voc.

Item Type: Article
Uncontrolled Keywords: laserbeam induced current; Cd0.9Zn0.1S; defects; photoresponse
Subjects: F200 Materials Science
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Becky Skoyles
Date Deposited: 23 Nov 2015 15:55
Last Modified: 29 Oct 2017 20:58
URI: http://nrl.northumbria.ac.uk/id/eprint/24700

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