Thickness effect on field electron emission of silicon emitter arrays coated with sol–gel Ba 0.65Sr 0.35TiO 3 and (Ba 0.65Sr 0.35) 0.75La 0.25TiO 3 thin films

Abstract

Ba 0.65Sr 0.35TiO 3 (BST) and (Ba 0.65Sr 0.35) 0.75La 0.25TiO 3 (BSLT) thin films with different thicknesses have been deposited onto silicon field emitter arrays (FEAs) using sol–gel technology for field electron emission applications. The BST-coated Si FEAs demonstrate an enhancement of electron emission, but the threshold field is BST film thickness dependence. The study reveals that the film thickness dependence of electron emission is due to the various microstructural features developed in BST films with different thicknesses. The crystallinity in perovskite films is improved with the increasing film thickness. The 15-nm-thick BST film is amorphous in nature, and then the polycrystalline perovskite grains are formed on the top of the amorphous layer in the thicker film. BSLT-coated Si FEAs also exhibit similar thickness-dependent field emission enhancement behavior, but thick BSLT samples (≥ 60 nm) have much significant enhancement of field emission compared with similar thickness BST samples due to effective supply of emitted electrons in the bulk region of electron-doped BSLT coatings.