Bharat Jalan

Adsorption-controlled growth and the influence of stoichiometry on electronic transport in hybrid molecular beam epitaxy-grown BaSnO3 films

Co-reporter:Abhinav Prakash;Peng Xu;Xuewang Wu;Greg Haugstad;Xiaojia Wang

Journal of Materials Chemistry C 2017 vol. 5(Issue 23) pp:5730-5736

Publication Date(Web):2017/06/15

DOI:10.1039/C7TC00190H

High room-temperature electron mobility and optical transparency in the visible spectrum distinguishes BaSnO3 from other perovskite oxides. The origin of low mobility in thin films as compared to their bulk counterpart is attributed to the presence of dislocations in films with nearly no discussion on the role of point defects such as cation non-stoichiometry. Using high-resolution X-ray diffraction, Rutherford backscattering spectrometry, thermal, and electronic transport measurements, we show that a growth window, in which cation stoichiometry is self-regulating, can be achieved for BaSnO3 films on SrTiO3(001) and (La0.3Sr0.7)(Al0.65Ta0.35)O3(001) (LSAT) substrates using a hybrid molecular beam epitaxy approach. BaSnO3 films on SrTiO3 grown within the growth window yielded a mobility value of 105 cm2 V−1 s−1 at a density, 2.5 × 1020 cm−3. Bulk-like thermal conductivity of 13.3 ± 1.46 W m−1 K−1 was achieved for stoichiometric films. Both Ba- and Sn-deficient films resulted into charge compensation and low mobility, with a stronger dependence for Sn-deficient films.

Quasi 2D Ultrahigh Carrier Density in a Complex Oxide Broken-Gap Heterojunction

Co-reporter:Peng Xu;Timothy C. Droubay;Jong Seok Jeong;K. Andre Mkhoyan;Peter V. Sushko;Scott A. Chambers

Advanced Materials Interfaces 2016 Volume 3( Issue 2) pp:

Publication Date(Web):

DOI:10.1002/admi.201500432

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 GdTiO₃/SrTiO₃ interfaces, and is typically an order of magnitude lower at LaAlO₃/SrTiO₃ 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 SrTiO₃ (8 u.c.)/NdTiO₃ (t u.c)/SrTiO₃ (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.

Adsorption-controlled growth and the influence of stoichiometry on electronic transport in hybrid molecular beam epitaxy-grown BaSnO3 films

Co-reporter:Abhinav Prakash, Peng Xu, Xuewang Wu, Greg Haugstad, Xiaojia Wang and Bharat Jalan

Journal of Materials Chemistry A 2017 - vol. 5(Issue 23) pp:NaN5736-5736

Publication Date(Web):2017/02/08

DOI:10.1039/C7TC00190H

High room-temperature electron mobility and optical transparency in the visible spectrum distinguishes BaSnO3 from other perovskite oxides. The origin of low mobility in thin films as compared to their bulk counterpart is attributed to the presence of dislocations in films with nearly no discussion on the role of point defects such as cation non-stoichiometry. Using high-resolution X-ray diffraction, Rutherford backscattering spectrometry, thermal, and electronic transport measurements, we show that a growth window, in which cation stoichiometry is self-regulating, can be achieved for BaSnO3 films on SrTiO3(001) and (La0.3Sr0.7)(Al0.65Ta0.35)O3(001) (LSAT) substrates using a hybrid molecular beam epitaxy approach. BaSnO3 films on SrTiO3 grown within the growth window yielded a mobility value of 105 cm2 V−1 s−1 at a density, 2.5 × 1020 cm−3. Bulk-like thermal conductivity of 13.3 ± 1.46 W m−1 K−1 was achieved for stoichiometric films. Both Ba- and Sn-deficient films resulted into charge compensation and low mobility, with a stronger dependence for Sn-deficient films.

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