High-temperature trapping of muons in CuInSe2 and CuInS2

Abstract

Zero-field [mu]SR measurements were performed at the EMU muon beamline of the ISIS facility on single crystals of p- and n-type CuInSe2 and on crystallites of p-type CuInS2.The diamagnetic centre, thought to be located in all these compounds at the Se anti-bonding interstitial site at low temperatures, is seen to diffuse above 200 K in the Se compound and above 250 K in the S compound. At 380 K the muons are again motionless in CuInSe2. This is evidence that the muons are trapped at defects. The fitted low values of the static dipolar width at the trapping sites are consistent with a static muon in a vacancy. This interpretation implies a vacancy concentration in the order of 1020 cm-3, unless the trapping radius is particularly large. However, defects other than vacancies may be involved.