Origin of the superior conductivity of perovskite Ba(Sr)SnO3

Abstract

ASnO 3 (A ¼ Ba, Sr) are unique perovskite oxides in that they have superior electron conductivity despite their wide optical band gaps. Using first-principles band structure calculations, we show that the small electron effective masses, thus, good electron conductivity of ASnO 3 can be attributed to the large size of Sn in this system that gives the conduction band edge with antibonding Sn and Os characters. Moreover, we show that ASnO 3 can be easily doped by La with shallow La A (þ/0) donor level. Our results, therefore, explain why the perovskite BaSnO 3 , SrSnO 3 , and their alloys are promising candidates for transparent conducting oxides. V C 2013 American Institute of Physics.

Structure and optical band gaps of (Ba,Sr)SnO3 films grown by molecular beam epitaxy

“…Density functional theory (DFT) values also differ greatly. 6,[13][14][15][16] Several factors affect the measured band gaps. Optical absorption is likely dominated by the direct band gap.…”

Transparent conducting properties of SrSnO3 and ZnSnO3

“…Infrared measurements of phonon frequencies for BaSnO 3 have been reported, 38 along with several calculations. 22,23,39 In comparing the three materials, BaSnO 3 , SrSnO 3 , and ZnSnO 3 , another effect of phonons may also be important. Specifically, high dielectric constants can lead to higher mobility due to screening of defects.…”

“…18 As mentioned, BaSnO 3 shows considerable promise as a new n-type transparent conducting oxide (TCO). This material, which has a simple s-band electronic structure, 17,[19][20][21][22][23][24] is dopable to a highly conductive state using Sb or La, 25 and has been developed as a high performance TCO. [6][7][8][9][10][11][12] The related compounds, CaSnO 3 and SrSnO 3 , occur in distorted orthorhombic perovskite structures, 26 while ZnSnO 3 occurs in a ferroelectric LiNbO 3 type structure.…”

High field-effect mobility at the (Sr,Ba)SnO3/BaSnO3 interface

“…15,16 In contrast to previous FETs using La-doped BaSnO 3 conducting channels, 12-14 the present FET on non-doped, insulating ones would have an advantage for applications in that a normally-off device with higher current on/off ratio can be developed. Previous studies aiming at improving characteristics of La-doped BaSnO 3 FETs focused on selection of appropriate gate dielectrics and suitable deposition methods that could reduce trap density at the gate dielectric/channel interface. [12][13][14] In particular, epitaxial LaInO 3 barrier/La-doped Figure 2 illustrates the cross-sectional schematic of the heterostructure and the plausible band diagram under applying positive V GS .…”

“…Distinct from transition-metal-based perovskites where strong electron correlation and spin-orbit coupling originating from d orbital character play important roles, BaSnO 3 possesses a highly dispersive conduction band predominantly composed of Sn 5s orbitals, which leads to relatively small electron effective mass of 0.20m 0 (where m 0 is the free electron mass) and high electron mobility. 3 One of obvious research targets of the exceptionally high mobility is field-effect transistor (FET) that employs a non-doped BaSnO 3 film as the channel. FET allows for electric-field control of high-mobility charge carrier transport at two-dimensional interface as well as practically useful switching function.…”