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Real time observation of phase formations by XRD during Ga‐rich or In‐rich Cu(In, Ga)Se 2 growth by co‐evaporation
Author(s) -
Pistor Paul,
ZahediAzad Setareh,
Hartnauer Stefan,
Wägele Leonard A.,
Jarzembowski Enrico,
Scheer Roland
Publication year - 2015
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201431949
Subject(s) - evaporation , materials science , selenide , stoichiometry , analytical chemistry (journal) , phase (matter) , solar cell , diffraction , vacancy defect , crystallography , chemistry , metallurgy , optoelectronics , optics , thermodynamics , selenium , physics , chromatography , organic chemistry
Solar cells with Cu(In, Ga)Se 2 absorbers rely on the three‐stage co‐evaporation process with Cu‐poor/Cu‐rich/Cu‐poor absorber deposition conditions for highest efficiency devices. During the three‐stage process, the formation and evolution of different selenide phases with changing compositions throughout the process crucially determine the final absorber quality. In this contribution, we monitor the evolution of crystalline phases in real‐time with an X‐ray diffraction (XRD) line detector setup implemented into an evaporation setup. Using the common three‐stage process, we prepare and compare samples covering the full alloying range from CuInSe 2 to CuGaSe 2 . The in situ XRD allows the detection of the crystalline phases present at all times of the process as well as an advanced analysis of the phase evolution through a closer look at peak shifts and the full width at half maximum. For samples with a Ga/(Ga + In) ratio (GGI) < 0.5, distinct phase transitions associated with the transition to the reported vacancy compounds Cu(In,Ga) 5 Se 8 and Cu(In, Ga) 3 Se 5 are observed. No such indication was found for samples with a GGI > 0.5. For Ga‐rich Cu(In, Ga)Se 2 phases with a GGI of 0.55, the XRD analysis evidenced a Ga‐rich phase segregation before the stoichiometric point was reached. The above findings are discussed in view of their implication on wide gap solar cell performances.