1% La doped BaSnO3 thin films of different thicknesses, ranging from 15 to 300 nm, were obtained on single crystal Lanthanum Aluminate-Strontium Aluminate Tantalate [LSAT(001)] substrates via Pulsed Laser Deposition. The films grow epitaxially on these substrates (cube-on-cube epitaxy) and are almost relaxed with a strain of ≈0.51% for 300 nm films. All films show n-type conducting behavior with their conductivity varying from 65.36 S cm−1 to 465.11 S cm−1 as the thickness of the film is increased. Low temperature carrier concentration measurements indicate that the films are degenerate semiconductors. Films with a thickness ≥30 nm exhibit metal to semiconductor transition (MST) at low temperatures. Temperature dependent resistivity analysis of the films shows evidence of electron-electron interaction rather than weak localization as the governing transport mechanism below MST. The transition temperature shifts toward lower values at higher thicknesses, strengthening the metallic transport in such films.

No abstract

Highly conducting and transparent thin films of La x Ba1 − x SnO3 (x = 0, 0.01 and 0.05) were grown on quartz substrates via pulsed laser deposition. Conductivity increases in orders of magnitude upon vacuum annealing of the as–deposited films. This is attributed to the significant enhancement in carrier concentration due to the increased oxygen vacancy defects (V O ∙ ∙ ). Enhanced carrier concentration improves the metallicity in the films at room temperature. Metal to semiconductor transition (MST) is observed in the films with n e ⩾ 1019 cm−3 at low temperatures. The MST shifts towards absolute zero temperature as the carrier concentration in the film increases. Low–temperature resistivity analysis suggests that the charge transport is mainly governed by strong electron–electron interaction. UV–Vis spectroscopy confirms a 60%–80% transmittance in the visible range (400–800 nm) for all the films. Due to the large change in carrier concentration, Burstein Moss (BM) shift is observed, and the bandgap ranges between 3.65–3.98 eV. The effective mass of electron and refractive index estimated from the BM shift and transmittance are found to be 0.6 m e and 2, respectively.