Optical and electrical properties of ZnOCdTe thin films

Films of ZnOCdTe have been deposited by reactive sputtering using as starting materials CdTe crystalline powder spreaded on a ZnO target and covering a fraction of the target area. The I composition of the sputtering gas was, respectively, 100% Ar, 10% H-2/Ar, 20% H-2/Ar. Films deposited in different conditions have been characterized from a structural, optical and electrical point of view. Three different series of samples have been investigated with different percentage of CdTe (10%, 30% and 60% of the target area covered by CdTe powder) and different composition of the sputtering gas. X-ray diffraction evidences a polycrystalline structure for samples deposited with 10% and 30% of CdTe and an amorphous structure for samples deposited with 60% of CdTe. Optical transmission measurements evidence a dependence of absorption coefficient on the percentage of hydrogen in the gas sputtering mixture. Dark conductivity has been measured as a function of temperature in the range 20 K- 300 K. More than one mechanism seem to contribute to electrical transport.