Photoresist template fabrication and template assisted growth for surface patterning of technologically important Cu2ZnSnSe4 thin films

Abstract

We present the details of fabrication route for photoresist template, which is useful in surface texturing of technologically important thin films such as solar absorbers, transparent conducting oxides (TCOs) and metals. Texturing improves the surface dependent properties such as absorption and anti-reflection. The compatibility of the positive photoresist (ALLRESIST ARP-3250) template for the growth of surface patterned quaternary solar absorber compound Cu2ZnSnSe4 (CZTSe) is evaluated. The reason for patterning the absorber layer is to induce light trapping effects for increased light absorption. The process use i-line masked optical lithography for the preparation of resist template over the continuous e-beam evaporated CZTSe film on glass substrate. The resist template assists the second time e-beam evaporation growth of well-defined array of CZTSe cuboids on continuous CZTSe. After the second deposition, the ARP-3250 resist template was removed to obtain the solar absorber layer on glass substrate, which present regular periodic array of cuboids on its surface. Optical microscopy, secondary electron microscopy (SEM) and Raman studies were done to study the effectiveness of the overall process in faithful pattern transfer and phase integrity of the surface patterned CZTSe. Optical absorbance measurements on patterned CZTSe films showed considerable increment in absorption compared to continuous film.