Influence of Plume Properties on Thin Film Composition in Pulsed Laser Deposition

Abstract

Despite the apparent simplicity of pulsed laser deposition, consistent deposition of thin films with the desired thickness, composition, crystallinity, and quality still remains challenging. This article explores the influence of process parameters with respect to film thickness and composition, two key aspects for thin films which have a very strong effect on film properties, possible applications, and characterization. Using five perovskite materials, a systematic analysis of different process parameters, e.g., target material, deposition pressure, fluence, substrate temperature or target to substrate distance, is performed. The results are classified under target ablation, plasma expansion, and substrates effects, which provide vital guidance to reduce the degree of trial and error when producing thin films. Moreover, they enable the understanding of what should be considered, and avoided for the deposition of thin films.

Revealing Strain Effects on the Chemical Composition of Perovskite Oxide Thin Films Surface, Bulk, and Interfaces

“…The RBS spectra have flat tops, within the statistical error margins, and RUMP fitting estimated the La/Sr ratio varies by less than 4% throughout the films (see Figure S8, Supporting Information). Target element atomic mass ratios play a key role in determining the composition of thin films deposited by PLD and previous work has demonstrated that lighter elements are often lower in content . This accounts for the deviation in the LSMC stoichiometry which has a lower cobalt content compared to bulk LSMC for films under both compressive and tensile strain.…”

High Carrier Mobility, Electrical Conductivity, and Optical Transmittance in Epitaxial SrVO3 Thin Films

“…It is worth to stress that whereas it is known that the Sr 3 V 2 O 8 phase is formed under relatively rich oxygen atmosphere, here its presence becomes more prominent at nominally the same oxygen pressure (residual vacuum) but under higher P (Ar). A possible explanation could be that when increasing Ar pressure, scattering of plasma species increases, being more prominent for the lighter elements, and thus a V deficient flux of adatoms should be expected at the film surface, eventually leading to the formation of a substoichiometric ([V/Sr] < 1) oxide, such as Sr 3 V 2 O 8 . The [Sr/V] concentration ratio in the SVO film and its dependence on P (Ar) has been explored by using energy dispersive X‐ray spectroscopy (EDX) and X‐ray photoemission spectroscopy (XPS) (Figure S6, Supporting Information).…”

“…This observation implies that the growth process has a large effect on the carrier mobility (and hence the electrical conductivity), probably related to the presence of growth‐induced defects in the film. Indeed, in PLD technique, the use of ultralow pressure (≈10 −7 mbar) during growth has important consequences on the spatial expansion and kinetic energy of the ablated species as well as on the self‐sputtering and backscattering processes . Probably the most obvious is that energetic species can impinge upon the substrate and the growing film, with subsequent creation of various defects including nonstoichiometry.…”

Photoconversion Optimization of Pulsed-Laser-Deposited p-CZTS/n-Si-Nanowires Heterojunction-Based Photovoltaic Devices

“…Indeed, PLD has been demonstrated to be highly effective for growing highly crystallized PbS nanoparticles at room temperature [20,21]. Moreover, the PLD offers the required process latitude to control the composition, microstructure and hence the optoelectronic properties of the produced thin films by almost independently adjusting the various PLD processing parameters, such as laser fluence, repetition rate, substrate temperature, background gas pressure, and the number of laser ablation pulses [22][23][24]. For the PLD of CZTS films, Vanalakar et al have specifically underlined the great progress achieved in the PCE of pulsed-laser-deposited CZTS (PLD-CZTS)-based solar cells over the last few years [25].…”