An improved continuous compositional-spread technique based on pulsed-laser deposition and applicable to large substrate areas

Abstract

A new method for continuous compositional-spread (CCS) thin-film fabrication based on pulsed-laser deposition (PLD) is introduced. This approach is based on a translation of the substrate heater and the synchronized firing of the excimer laser, with the deposition occurring through a slit-shaped aperture. Alloying is achieved during film growth (possible at elevated temperature) by the repeated sequential deposition of sub-monolayer amounts. Our approach overcomes serious shortcomings in previous in-situ implementations of CCS based on sputtering or PLD, in particular the variations of thickness across the compositional spread and the differing deposition energetics as function of position. While moving-shutter techniques are appropriate for PLDapproaches yielding complete spreads on small substrates (i.e. small as compared to distances over which the deposition parameters in PLD vary, typically ≈ 1 cm), our method can be used to fabricate samples that are large enough for individual compositions to be analyzed by conventional techniques, including temperaturedependent measurements of resistivity and dielectric and magnetic and properties (i.e. SQUID magnetometry). Initial results are shown for spreads of (Sr 1-x Ca x )RuO 3 .2

Structure, physical properties, and applications ofSrRuO3thin films

“…The ability to tune the lattice parameters allows growth of epitaxial multilayers with many complex oxides. Christen et al (2003) used this same material system as a model to demonstrate a compositional spread method. Finally, Goto (2008a, 2008b) used Ba-substituted SrRuO 3 on quartz in their research on tailored buffer materials [see also Fukushima et al (1998) and H. C. .…”

Advances in the growth and characterization of magnetic, ferroelectric, and multiferroic oxide thin films

“…Application of this technique, however, has been limited due to difficulty in analyzing the resulting materials. Regardless, elegant processes to enable laterally varying compositional spreads have been developed, including utilization of the directed nature of PLD growth via synchronized substrate motion and laser firing [22] or the introduction of an aperture between target and substrate [23]. Other studies have focused on temperature -one of the most critical parameters in PLD film growth -and ways to cover large thermodynamic phase spaces in relatively short times.…”

Continuous composition spread using pulsed-laser deposition with a single segmented target

“…In order to achieve a continuous composition spread by using PLD, two targets, A and B, have been ablated sequentially and either a mask is moved in front of the substrate to partially shadow one or the other target 10 or the substrate is moved behind a mask to realize lateral composition spread. 12 Both approaches yield a linear composition gradient and have proved useful for creating material libraries. However, for both approaches, movable parts (shadow mask, substrate holder) have to be introduced to the vacuum chamber.…”