CdTe:Bi films deposited by closed space vapor transport under variable pressure and doping levels: evidences of the possible formation of an intermediate band

Abstract

In this work, the results about the properties of CdTe:Bi thin films grown by the Closed Space Vapor Transport (CSVT) method are presented. Two procedures were developed for the CdTe:Bi films deposition: (a) using powders with different Bi concentrations at a constant pressure in the CSVT chamber and (b) varying the total final Ar pressure in the CSVT chamber. The CdTe powders used in our experimental conditions were obtained by using CdTe:Bi crystals grown by the vertical Bridgman method, varying the nominal Bi-dopant concentration in the 1.0 × 1017 to 4 × 1019 at/cm3 range. Finally, the possible influence of both parameters on the existence of an intermediate band in CdTe:Bi thin films and CdS/CdTe solar cell characteristics is analyzed.