Controlling surface carrier density by illumination in the transparent conductor La-doped BaSnO3

Abstract

LaxBa1-xSnO3 is a promising transparent conducting oxide whose high mobility facilitates potential applications in transparent electronics, oxide electronics, and power electronics. Here, we report quantitative comparisons between angle-resolved photoemission and density functional theory, demonstrating a close agreement between calculations and the measured bulk electronic structure. Further measurements reveal upward band bending at the film-vacuum interface, while ultraviolet (UV) exposure is found to increase the surface electron density, similar to other oxides. These results elucidate the LaxBa1-xSnO3 (LBSO) interfacial electronic structure and offer a route for UV carrier density control, critical steps towards realizing LBSO-based electronic devices.

Reversible Manipulation of Photoconductivity Caused by Surface Oxygen Vacancies in Perovskite Stannates with Ultraviolet Light

“…The strong dependence of I P – t characteristics on oxygen partial pressure during light illumination (Figure S4, Supporting Information) represents that oxygen‐related trapping states in BaSnO 3 should be responsible for the difference in photoresponsivity and relaxation in these photodetectors. [ 7c,13 ]…”

“…In vacuum‐illuminated BaSnO 3 photodetectors, R ph ≈ 3 μA W −1 was detected at the threshold E ph ≈ 2.53 eV, in addition to R ph from bandgap transition ( E ph > 3.1 eV); the photoresponse at 2.53 eV < E ph < 3.1 eV indicates that in‐gap state can be produced after ultraviolet illumination of BaSnO 3 photodetectors under vacuum. [ 7c,13,15 ]…”

2×2R45∘ surface reconstruction and electronic structure of BaSnO3 film

“…For that reason, the electronic structure has been investigated by using first principles and tight-binding calculations 24,[29][30][31][34][35][36][37][38][39][40] . As for the experimental determination of the band structure, it has been limited to couple of angle-resolved photoemission spectroscopy (ARPES) studies on BSO 7 and BLSO films 8 which suggest for an indirect band gap 7 and an upward band bending at the vacuum interface 8 . However, the study on BSO was performed on a 8 nm thick film on SrTiO 3 (STO) substrate without a buffer layer and possible existence of defects originating from lattice mismatch between BSO film and STO substrate makes it unclear if the results represents the intrinsic property of BSO.…”

Surface state at $BaSnO_3$ evidenced by angle-resolved photoemission spectroscopy and ab initio calculations

“…Furthermore, both BSO and SSO in thin-film form showed a further improvement in light transparency, electrical conductivity [12,13] and high electron mobility generally attributed to a small electron effective mass in the range of 0.2-0.4m e [14][15][16][17][18]. Significant theoretical and experimental efforts [19] have been made to understand these unique electronic properties. Band structure calculations, based on density functional theory (DFT), found small effective masses for conducting state of bulk BSO [18], caused by a substantial reduction in the electron-phonon scattering rate.…”

“…In general, the breaking of translation symmetry on the surface may result in a new state whose wave function localized at the surface [27], and has different properties than the bulk band. Doping via oxygen vacancies, in cooperation with downward band bending, has been proposed to explain the formation of the 2-dimensional state in SrTiO 3 surfaces and interfaces [4][5][6], but this is not likely to be the case for BSO films based on the observation of an upward band bending by photoemission spectroscopy [19]. To investigate the origin of the experimentally observed 2D states, we performed DFT(GGA-PBE) calculations for BSO slabs on (001) surface, with both SnO 2 and BaO terminations.…”