2DEGs at Perovskite Interfaces between KTaO3 or KNbO3 and Stannates

Abstract

We report density functional studies of electron rich interfaces between KTaO3 or KNbO3 and CaSnO3 or ZnSnO3 and in particular the nature of the interfacial electron gasses that can be formed. We find that depending on the details these may occur on either the transition metal or stannate sides of the interface and in the later case can be shifted away from the interface by ferroelectricity. We also present calculations for bulk KNbO3, KTaO3, CaSnO3, BaSnO3 and ZnSnO3, showing the different transport and optical properties that may be expected on the two sides of such interfaces. The results suggest that these interfaces may display a wide range of behaviors depending on conditions, and in particular the interplay with ferroelectricity suggests that electrical control of these properties may be possible.

Structure and transport in high pressure oxygen sputter-deposited BaSnO3−δ

“…13,16 The fundamental understanding of BSO has also improved, including its electronic structure in bulk, 10,[17][18][19][20][21][22] as well as its phonon spectrum, 17 optical properties, 10,11,17,[20][21][22]26 scattering mechanisms, 10,[13][14][15]27 defects, 28 and thermal stability. 9 It is understood that the conduction band is derived from Sn 5s states 10,[17][18][19][20][21][22][23][24][25] and progress is being made in identifying mobility-limiting mechanisms in crystals [9][10][11] and films. 9,10,[13][14][15]27 There remain a number of unresolved issues, however, including the optimal choice of dopant ion and site 13 and the relative importance of phonon, 11,17 neutral impurity, ionized impurity, 9,…”

Transparent conducting properties of SrSnO3 and ZnSnO3

“…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.…”

Tuning optical properties of transparent conducting barium stannate by dimensional reduction

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Importantly, recent studies of high mobility La doped BaSnO 3 transparent conducting films show transport properties that are still dominated by extrinsic defects, specifically dislocations. 12,18,19 The implication is that there remains considerable room for even better conductivity with improvements in film perfection.…”

“…12,18,19 The implication is that there remains considerable room for even better conductivity with improvements in film perfection. Recent studies suggested that n-type BaSnO 3 may have substantial tunability, e.g., in the band gap via alloying and strain, [14][15][16][17] but applications of strain tuning of BaSnO 3 have yet to be demonstrated. Here, we show that it is possible to tailor the spectral transmission of BaSnO 3 by a dimensional reduction strategy.…”

“…This potential gives band gaps in remarkably good accord with experiment for a wide variety of simple semiconductors and insulators, [42][43][44][45][46] including perovskite stannates. 15 We compared the TB-mBJ results for the undoped compounds with HSE06 calculations as discussed below.…”