Fabrication of spectrally selective tandem stack of HfZrC/HfZrCN/HfZrON/HfZrO by reactive magnetron sputtering for CSP applications

Abstract

A novel HfZrC/HfZrCN/HfZrON/HfZrO based solar absorber tandem stack was successfully deposited on silicon and stainless steel (SS) substrates by pulsed DC reactive magnetron sputtering using an alloy target of HfZr. The optimized tandem stack was fabricated by varying the deposition parameters like reactive gas flow rates (C2H2, N2, and O2), sputtering power, and deposition time. X-ray diffraction and X-ray photoelectron spectroscopic methods were used to determine the structural and chemical compositions present in the optimized tandem coatings. In the tandem stack, HfZrC, HfZrCN and HfZrON/HfZrO layers act as a main absorber layer, a semi-absorber layer and double layer anti-reflection in the coating structure. The high spectral selectivity was achieved by optimizing the individual layers in the tandem stack, which exhibits 0.947 of optical absorptance in the solar region and 0.14 of low emissivity in the IR region. The optimized tandem stack is stable up to a temperature of 500 °C in a vacuum environment. The present investigation demonstrates that the developed HfZrC/HfZrCN/HfZrON/HfZrO tandem stack exhibited high solar spectral selectivity and good thermal stability, thus it can be used in high-temperature solar concentrated power applications.