Electrodeposition of CdTe Semiconductor from Ammoniacal Aqueous Solution

摘要

Electrodeposition of CdTe was studied usingaqueous ammonia-alkaline electrolytic baths in which Cd~II- andTe~IV- ions are dissolving as Cd~II (NG_3)_4~2+andTe~IVO_3~2- ions, respectively. Ca-thodic polarization curves ofthe baths suggest the presence of strong interaction between theCd~II- and Te~IV- ions; electrodeposition of tellurium is inhibitedby the presence of Cd (NH_3)_4~2+ ions. The interaction makes itpossible to electrodeposit CdTe films with stoichiometriccomposition. Polycrystalline CdTe thin film of about 1 #mu#mthickness was electrodeposited at 343 K from ammonia-alkalinesolutions (pH bounds 10.7) containing TeO_3~2-(< 20 mmoldm~-3) and Cd(NH_3)_4~2+ (< 60 mmol dm~-3) ions. IncreasingCd(NH_3)_4~2+/TeO_3~2- mole ratio or decreasing totalconcentration of ammonia/ammonium - ion gave flat and smoothcrystalline CdTe deposits at constant cathode potential -0.70 to -0.30 V vs SHE at 343 K.