Structural and spectroscopic studies of CdS/CdTe heterojunction cells fabricated by electrodeposition

CdTe films have been electrodeposited on CdS\SnO2 (F)\glass in a stirred ce ll and in a channel flow cell. The influence of deposition conditions on re crystallization during annealing treatment has been studied. Films were cha rarterised by XRD, photocurrent spectroscopy and electroreflectance/absorba nce spectroscopy using electrolyte contacts to allow illumination from the CdTe or CdS sides. As-deposited CdTe is generally n-type and tends to show strong preferential [1 1 1] orientation. Thermal treatment in air brings ab out type conversion. Type conversion is not necessarily accompanied by recr ystallization; most of the CdTe films deposited from stirred solution did n ot recrystallize. Recrystallization did occur for films grown by pulsing th e potential periodically from 50 mV to >350 mV vs. Cd2+/Cd during depositio n. Tn this case, diffusion of sulfur led to formation of CdTe0.95S0.05. CdT e films were also electrodeposited rapidly in a channel flow cell. Depositi on times shorter than 30 min for 2 mu m were achieved. and the films recrys tallized fully during thermal annealing. The now cell films produced in thi s way gave reasonable solar cell performances, holding out the promise of m ore rapid fabrication of CdS/CdTe cells by electrodeposition. (C) 2000 Publ ished by Elsevier Science S.A. All rights reserved.