Using advanced ab initio calculations, we describe the formation and confinement of a two-dimensional electron gas in short-period (≃4-nm) Nb-doped SrTiO3 superlattices as a function of Nb doping. We predict complete two-dimensional confinement for doping concentrations higher than 70%. In agreement with previous observations, we find a large thermopower enhancement at room temperature. However, this effect is primarily determined by dilution of the mobile charge over a multitude of weakly occupied bands. As a general rule, we conclude that thermopower in similar heterostructures will be more enhanced by weak, rather than tight, spatial confinement.

Doping-induced dimensional crossover and thermopower burst in Nb-doped SrTiO3 superlattices

DELUGAS, Pietro Davide;
2013

Abstract

Using advanced ab initio calculations, we describe the formation and confinement of a two-dimensional electron gas in short-period (≃4-nm) Nb-doped SrTiO3 superlattices as a function of Nb doping. We predict complete two-dimensional confinement for doping concentrations higher than 70%. In agreement with previous observations, we find a large thermopower enhancement at room temperature. However, this effect is primarily determined by dilution of the mobile charge over a multitude of weakly occupied bands. As a general rule, we conclude that thermopower in similar heterostructures will be more enhanced by weak, rather than tight, spatial confinement.
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http://doi.org/10.1103/PhysRevB.88.045310
Delugas, Pietro Davide; Filippetti, A; Verstraete, Mj; Pallecchi, I; Marré, D; Fiorentini, V.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/32804
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