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Title: Reducing interface recombination for Cu(In,Ga)Se{sub 2} by atomic layer deposited buffer layers

Partial CuInGaSe{sub 2} (CIGS) solar cell stacks with different atomic layer deposited buffer layers and pretreatments were analyzed by photoluminescence (PL) and capacitance voltage (CV) measurements to investigate the buffer layer/CIGS interface. Atomic layer deposited ZnS, ZnO, and SnO{sub x} buffer layers were compared with chemical bath deposited CdS buffer layers. Band bending, charge density, and interface state density were extracted from the CV measurement using an analysis technique new to CIGS. The surface recombination velocity calculated from the density of interface traps for a ZnS/CIGS stack shows a remarkably low value of 810 cm/s, approaching the range of single crystalline II–VI systems. Both the PL spectra and its lifetime depend on the buffer layer; thus, these measurements are not only sensitive to the absorber but also to the absorber/buffer layer system. Pretreatment of the CIGS prior to the buffer layer deposition plays a significant role on the electrical properties for the same buffer layer/CIGS stack, further illuminating the importance of good interface formation. Finally, ZnS is found to be the best performing buffer layer in this study, especially if the CIGS surface is pretreated with potassium cyanide.
Authors:
;  [1] ; ; ; ; ;  [2]
  1. Department of Chemical Engineering, Stanford University, Stanford, California 94305 (United States)
  2. National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)
Publication Date:
OSTI Identifier:
22486360
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 3; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BUFFERS; CADMIUM SULFIDES; CAPACITANCE; CHARGE DENSITY; DENSITY; DEPOSITION; ELECTRIC POTENTIAL; INTERFACES; LAYERS; LIFETIME; MONOCRYSTALS; PHOTOLUMINESCENCE; POTASSIUM; SPECTRA; STACKS; SURFACES; TRAPS; ZINC OXIDES; ZINC SULFIDES