Al-delta-doped ZnO films made by atomic layer deposition and flash-lamp annealing for low-emissivity coating

In this work, we have investigated and optimized the Al-delta-doped ZnO (δ -AZO) superlattices for mid-infrared applications. Thin films of δ -AZO are fabricated by atomic layer deposition (ALD) followed by millisecond-range (ms-range) flash-lamp annealing (FLA). During the FLA process, the superlattice structure is preserved and Al is electrically activated. The highest carrier concentration and lowest resistivity estimated from Hall-effect measurements are 2.7 × 1021 cm−3 and 8.8 × 10-4 Ωcm, respectively, for the δ -AZO superlattice with an Al:Zn ratio of 1:20. Moreover, glass substrates coated with the developed δ -AZO superlattice show a reflectance above 60 % in the near- and mid-infrared spectral range, while the transmittance in the visible range maintains above 80 %. The presented δ -AZO superlattice is a good alternative material to replace indium tin oxide films for cost-efficient low-emissivity glazing.