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Quasi 2D Ultrahigh Carrier Density in a Complex Oxide Broken‐Gap Heterojunction
Author(s) -
Xu Peng,
Droubay Timothy C.,
Jeong Jong Seok,
Mkhoyan K. Andre,
Sushko Peter V.,
Chambers Scott A.,
Jalan Bharat
Publication year - 2016
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201500432
Subject(s) - heterojunction , materials science , perovskite (structure) , charge carrier density , oxide , condensed matter physics , band gap , charge carrier , electron , optoelectronics , crystallography , physics , doping , chemistry , quantum mechanics , metallurgy
Two‐dimensional (2D) ultra‐high carrier densities are of considerable current research interest for novel plasmonic and high charge‐gain devices. However, the highest 2D electron density obtained is thus far limited to 3 × 1014 cm–2 (½ electron/unit cell/interface) at GdTiO 3 /SrTiO 3 interfaces, and is typically an order of magnitude lower at LaAlO 3 /SrTiO 3 interfaces. We show from experiment and modeling that carrier densities much higher than expected based on resolution of the polar discontinuity at perovskite oxide heterojunctions can be achieved via band engineering. The SrTiO 3 (8 u.c.)/NdTiO 3 ( t u.c)/SrTiO 3 (8 u.c.)/LSAT(001) heterostructure shows the expected electronic reconstruction behavior starting at t = 2 u.c., but then exhibits a higher carrier density regime at t ≥ 6 u.c. due to additional charge transfer from band alignment.