Spatial variation of the elemental components of thin films from BiSrCaCuO target deposited using low energy femtosecond pulsed laser deposition in high background gas pressure

In this work, we investigated the spatial variation of the elemental composition of the thin films produced by low-energy femtosecond pulsed laser deposition with BiSrCaCuO (BSCCO) as the target material. In addition, the effect of high background gas pressure and gas type on the thin film elemental composition was also investigated. The background gas pressure was varied between 4, 50, and 100 mTorr, using nitrogen (N2) and argon (Ar) as the gases. MgO substrates were positioned at the center and at different distances from the center to analyze the spatial variation of the deposited film. Despite the low energy from the fs laser pulse and the high background gas pressure, the constitutive elements of BSCCO, namely, bismuth (Bi), strontium (Sr), calcium (Ca), and copper (Cu), were detected on the substrate. However, their relative ratios were not preserved in the thin film. To explain the results, a collision-based model and peak-fitting method of the angular distribution were employed. The study highlights the importance of proper substrate positioning and how background gas type and pressure influence material deposition, with N2 resulting in lower deposition due to enhanced energy transfer during ablation processes. The non-stoichiometric composition of the films and their spatial variation emphasize the limitations of current deposition models, pointing to the need for refined approaches that better predict film quality and elemental distribution.