In-situ and post-deposition heat treatment of femtosecond pulsed laser deposited ZnS on silicon (100) substrates

Abstract

The properties of thin films grown via pulsed laser deposition (PLD) can be controlled by varying growth parameters such as heat treatment. In this paper, the effects of in-situ and post-deposition heat treatment on the surface morphology and crystallinity of Zinc sulfide (ZnS) deposited on silicon (100) substrate via femtosecond PLD (fs-PLD) was investigated by characterizing the samples using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The as-deposited sample had coarse grains that are non-homogeneous in size with large gaps between coagulated grains. The sample became more compact with an increase in grain size after post-deposition heat treatment. The additional energy to the sample due to the heat treatment increased the surface mobility, allowing rearrangement into preferred growth directions, leading to a more compact sample surface. As the annealing temperature was increased, the grains became more uniform in size. After both in-situ and post-deposition heat treatment at 500⁰C, the XRD pattern of samples show peaks at 2θ = 33.19⁰ and 47.68⁰ corresponding to the (200) and (220) planes of cubic ZnS, indicating a polycrystalline structure.