A novel method of synthesizing p-CuInSe/sub 2/ thin films from the stacked elemental layers using a closed graphite box

Abstract

The stacked elemental layer (SEL) technique has been demonstrated as a method for producing films over a large area, but the films normally annealed in vacuum, mostly exhibited poor morphology with small grain sizes <1 /spl mu/m which result in poor devices. A novel method of fabricating CuInSe/sub 2/ films by annealing or selenization of the Cu, In and Se layers deposited onto Mo coated glass substrates in a closed graphite box was developed. SEM, EDX and XRD were used to characterize all films. Dense films with crystal sizes of about 4 /spl mu/m were obtained over an area of 15 cm/sup 2/. The mechanical properties of CuInSe/sub 2/ formed from various SEL sequences of In, Cu and Se layers on different substrates was also investigated. A sequence starting with an In layer (In/Cu/In/Se...) was found to produce the best adhesion on Mo coated glass, however, the adhesion was found to depend on the thickness of the first In layer. A thin In layer produced the best adhesion, increasing the thickness of the In layer resulted in poor adhesion. Devices with efficiency of 6.5% have been achieved using the absorbers processed in the graphite box. The low efficiency was due to a high series resistance in the cells.