Vacancy defects in epitaxial thin film CuGaSe2 and CuInSe2

Epitaxial thin film CuGaSe2 and CuInSe2 samples grown on GaAs substrates with varying [Cu]/[Ga,In] ratios were studied using positron annihilation Doppler-broadening spectroscopy and were compared to bulk crystals. We find both Cu monovacancies and Cu-Se divacancies in CuInSe2, whereas, in CuGaSe2, the only observed vacancy defect is the Cu-Se divacancy.Peer reviewe

Influence of post-deposition selenium supply on Cu(In,Ga)Se2-based solar cell properties

International audienceCu(In,Ga)Se2 (CIGSe) layers have been deposited by the 3-stage process and once the growth was completed, the structures have been kept at high temperature for 50 min with or without Se supply. Both the resulting CIGSe layer and related device properties are compared with those obtained when the substrate is cooled down right after the deposition. Moreover, such experiments have been performed with and without alkali availability. The results show that keeping the absorber at high temperature differently impacts [Ga] / ([In + Ga]) atomic ratio distribution and crystalline preferential orientation depending on whether Se is supplied. Moreover, this work shows that chalcogen supply can be detrimental for cell performance when the CIGSe contains alkali and in contrast be beneficial when the CIGSe is free of alkali. These observations suggest an intimate relationship between alkali and Se

A calorimetric particle detector using an iridium superconducting phase transition thermometer

We report on a calorimetric particles detector consisting of an 18.3 g silicon crystal and an iridium superconducting phase transition thermometer. The cryogenic calorimeter and the associated apparatus are described in detail. The pulses from irradiation with an #alpha#-particle source have a large unexpected overshoot in addition to the component expected from a naive thermal model. The pulse height spectrum displays an energy resolution of 1 percent FWHM at 6 MeV and good linearity. The noise, electrothermal feedback, and position dependence are discussed. (orig.)Available from TIB Hannover: RR 2916(94-01) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman