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The influence of sodium on the molybdenum/Cu(In,Ga)Se-2 interface recombination velocity, determined by time resolved photoluminescence

 
: Jarzembowski, E.; Syrowatka, F.; Kaufmann, K.; Fränzel, W.; Hölscher, T.; Scheer, R.

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Applied Physics Letters 107 (2015), No.5, Art. 051601
ISSN: 0003-6951 (Print)
ISSN: 1077-3118
ISSN: 1931-9401 (online)
English
Journal Article
Fraunhofer CSP ()

Abstract
In this work, glass/diffusion barrier/Mo/Cu(In,Ga)Se-2 stacks with and without adding NaF are investigated with the goal to determine the back surface recombination velocity. The absorber layers prepared by a three-stage co-evaporation process are characterized by time resolved photoluminescence (TRPL) and time of flight-secondary ion mass spectroscopy (TOF-SIMS). By comparison of experimental TRPL data with simulated TRPL transients calculated with Synopsys TCAD, Mo/Cu(In,Ga)Se-2 interface recombination velocities for electrons of S-b,S-n <= 1 x 10(2) cm/s (with NaF) and S-b,S-n >= 1 x 10(5) cm/s (without NaF) are determined. SIMS analysis points towards differences in alkali metal concentrations at the back contact being the origin of different S-b,S-n values. Our results shine light on the large spread of experimental S-n values reported in the literature and reveal another hitherto unknown effect of alkali doping in Cu(In,Ga)Se-2 semiconductors.

: http://publica.fraunhofer.de/documents/N-369588.html