TY  - JOUR
AU  - Gunkel, Felix
AU  - Waser, R.
AU  - Ramadan, Amr H. H.
AU  - De Souza, Roger A.
AU  - Hoffmann-Eifert, Susanne
AU  - Dittmann, Regina
TI  - Space charges and defect concentration profiles at complex oxide interfaces
JO  - Physical review / B
VL  - 93
IS  - 24
SN  - 2469-9950
CY  - College Park, Md.
PB  - APS
M1  - FZJ-2016-03490
SP  - 245431
PY  - 2016
AB  - We discuss electronic and ionic defect concentration profiles at the conducting interface between the two wide-band-gap insulators LaAlO3 and SrTiO3 (STO). The profiles are deduced from a thermodynamic model considering a local space charge layer (SCL) originating from charge transfer to the interface region, thus combining electronic and ionic reconstruction mechanisms. We show that the electrical potential confining the two-dimensional electron gas (2DEG) at the interface modifies the equilibrium defect concentrations in the SCL. For the n-conducting interface, positively charged oxygen vacancies are depleted within the SCL, while negatively charged strontium vacancies accumulate. Charge compensation within the SCL is achieved by a mixed ionic-electronic interface reconstruction, while the competition between 2DEG and localized ionic defects is controlled by ambient pO2. The concentration of strontium vacancies increases drastically in oxidizing conditions and exhibits a steep depth profile towards the interface. Accounting for the low cation diffusivity in STO, we also discuss kinetic limitations of cation defect formation and the effect of a partial equilibration of the cation sublattice. We discuss the resulting implications for low temperature transport
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000378816000014
DO  - DOI:10.1103/PhysRevB.93.245431
UR  - https://juser.fz-juelich.de/record/810924
ER  -