Enhanced Photoresponse of High Crystalline Bi2Se3 Thin-Films Using Patterned Substrates.

Abstract

High-quality Bi2Se3 thin films with topological insulating properties at room temperature have recently attracted much attention as one of the promising materials for realizing innovative electronic and optoelectronic devices. Here, we report the high crystallinity growth of Bi2Se3 thin films on a patterned sapphire substrate (PSS) by using a vapor-phase transport deposition with minimizing thermal dissociation of Se atoms vaporized in Bi2Se3 powder. This PSS not only reduces the large dislocation of heterogeneously grown Bi2Se3 on a sapphire substrate but also induces enhanced light absorption in the visible to near-infrared (IR) ranges compared to Bi2Se3 on planar sapphire substrates. Thus, the Bi2Se3 thin film laterally grown on the PSS reveals uniform surface properties and high crystallinity in the rhombohedral lattice phase with a full width at half maximum of 0.06° for the XRD (003) peak. Also, the photoresponse of the fabricated IR conversion device using Bi2Se3/PSS heterostructure exhibits excellent performance and high reliability with no degradation after continuous switching. As a result, the device constructed with the Bi2Se3/PSS exhibits one order of magnitude higher NIR induced-photocurrent and 1-2 orders of magnitude faster photo-switching than that with Bi2Se3/Al2O3. Such an enhancement in the device performance of Bi2Se3/PSS is confirmed by the increased absorption spectra in visible and NIR ranges and the improved light absorption distribution.