JUNCTION FORMATION AND CHARACTERISTICS OF CDS/CUINSE2/METAL INTERFACES

Polycrystalline thin films of CuInSe2 (CIS) were prepared by galvanic electrochemical (EC) and physical vapor deposition (PVD) methods and were characterized using high resolution photoluminescence at low temperatures to study defect states, scanning electron microscopy to study surface morphology, and transmission electron microscopy to determine the grain size and individual crystallographic orientation of the grains for possible correlation between the properties of the two films. Metal contacts. Schottky devices in the form of Al/p-CIS, and CdS/p-CIS heterostructures were also prepared. The electrical properties of the resulting interfaces were investigated using current voltage (I-V) and capacitance voltage (C-V) characteristics, and by electron-beam-induced current measurements. Devices prepared from PVD films exhibited a higher generation factor G, sharp interfaces and the lowest density of interface states. On the contrary, devices of low G values (made from EC films) showed a much higher density of interface states with a high density of both shallow and deep traps, as detected by deep level transient spectroscopy. The results were used to correlate the resulting variation in the heterojunction characteristics and back contact behavior with the corresponding defect states dominating the CIS.