Optical Characterization of Thin Film CuxAlOy in the CdTe Device Configuration

Optical properties and band gap energy of solution processed p-type transparent Cu
x
AlO
y
thin film deposited on sodalime glass are determined using spectroscopic ellipsometry. This is a promising material for a p-type transparent back contact and passivation layer for thin film CdTe based solar cells. The direct optical band gap obtained from Tauc plot is found to be
$3.64 \pm 0.01\ \text{eV}$
. Further characterization is also done with this layer in the CdTe / CdS device stack. Cu
x
AlO
y
conformally coats and smoothens the CdTe surface on the CdTe / CdS device stack indicating improved surface quality and surface passivation.