Enhanced carrier density in Nb-doped SrTiO3 thermoelectrics

Abstract

We study epitaxial SrTiO3 interfaced with Nb-doped SrTi1-xNbxO3 (x = 0, 0.125, 0.25, 0.375, and 0.5) by full-potential density functional theory. From the electronic band structures obtained by our ab-initio calculations we determine the dependence of the induced metallicity on the Nb concentration. We obtain a monotonous increase of the carrier density with the Nb concentration. The results are confirmed by experiments for SrTi0.88Nb0.12O3 and SrTi0.8Nb0.2O3, demonstrating the predictive power and limitations of our theoretical approach. We also show that the Seebeck coefficient decreases monotonously with increasing temperature.

Dynamics of the metal-insulator transition of donor-dopedSrTiO3

“…n-STO is explored for functionalities as diverse as thermoelectricity [21][22][23], memristive switching [24][25][26], superconductivity [27,28], and photoelectrolysis [18,29]. In particular for the resistive switching behavior, the underlying physical mechanisms in devices based on n-STO are not understood in detail, and contradicting interpretations are under debate [25,[30][31][32][33][34].…”

The structure, electrical properties and chemical stability of porous Nb-doped SrTiO3– experimental and theoretical studies

“…[18][19][20][21] Based on various computational methods, insulator to metal transition, the position of Nb dopants (Ti, Sr or interstitial initial sites) within Nb-doped SrTiO 3 structure, partial ionic charges and unit cell size dependence on dopant as well as doping mechanism and properties and formation energies of substitutional or vacancy defects and dependence of electrical and optical properties on point defects has been studied. [22][23][24][25][26][27][28] Most of theoretical papers devoted to electrical properties of Nb-doped SrTiO 3 contain detailed analysis of electronic structure properties (DOS and bandstructure). 22,23,29 However, these papers were concerned with some heavy doping models (high niobium concentrations), most probably due to prohibitive requirements for computer power in the case of big supercell calculations, necessary to model (low dopant concentration) and only recently, the calculations of electronic structure and optical properties for smaller niobium concentration (0.74-2.5 at% of niobium, corresponding to approx.…”

Magnetic exchange interactions in Mn doped ZnSnAs2 chalcopyrite

“…The electronic exchange-correlation is described within the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) [19]. The wave function of the charge density and potential in the interstitial region is expanded up to l max = 10, as well as the energy cut-off of R MT .K max = 7.0 were kept fixed in our calculation, where R MT denotes the smallest atomic sphere radius and K max gives the magnitude of the largest K vector in the plane wave expansion.…”