Rectifying current-voltage characteristics of BiFeO3∕Nb-doped SrTiO3 heterojunction

Abstract

Epitaxial c-axis oriented BiFeO3 (BFO) thin films were deposited on (001) Nb-doped SrTiO3 (Nb-STO) substrates by pulsed laser deposition. Introducing Bi vacancies caused the BFO thin film to evolve to a p-type semiconductor and formed a p-n heterojunction with an n-type semiconductor Nb-STO. The current density versus voltage (J-V) and capacitance versus voltage (C-V) characteristics of the heterojunction were investigated. A typical rectifying J-V effect was observed with a large rectifying ratio of 5×104. Reverse C-V characteristics exhibited a linear 1∕C2 versus V plot, from which a built-in potential of 0.6V was deduced. The results show a potential application of BFO/Nb-STO heterojunction for oxide electronics.

Interface-dependent rectifying TbMnO3-based heterojunctions

“…3(c). The band gaps of NSTO and TMO are approximately 3.2 and 0.5 eV, 22,47,48 respectively. The Fermi level in NSTO should be near the bottom of the conduction band due to its heavy doping, whereas the Fermi level in TMO is close to the center of the band as a result of its low carrier density.…”

“…[9][10][11][12] Furthermore, TMO exhibits distinct magnetic phases in various temperature regimes: the collinear spin order of Mn ions sets in at a Neel temperature T N of 41 K; the ferroelectric phase emerges in the bc-spiral spin state below 28 K, and concurrently the magnetic and the polarization vectors orientate along the b and the c axis, respectively; finally, a phase transition at about 7 K appears as a result of the magnetic ordering of the Tb sublattice. 4 As the first step towards the oxide electronics, a wide range of transition metal oxides are exploited in various device concepts, such as Schottky-like junctions, [13][14][15][16] field-effect transistors, 17,18 a Email: tomwu@ntu.edu.sg; rmwang@buaa.edu.cn 2158-3226/2011/1(4)/042129/11 C Author(s) 2011 1, 042129-1 and p-n junctions, [19][20][21][22][23] which are the building blocks in conventional semiconductor electronics. 24 Among them, two-terminal junctions are often considered as the most fundamental one due to their ubiquitous presence in many devices with higher complexity.…”

Orientation-dependent potential barriers in case of epitaxial Pt–BiFeO3–SrRuO3 capacitors

“…Unfortunately, due to the unknown conduction type in BFO films it is difficult to establish which of the two interfaces ͑bottom SRO-BFO or top BFO-Pt͒ is reverse biased for a certain polarity. A recent study claims that BFO should be p-type due to the Bi loss, 18 whereas the oxygen vacancies introduce conduction electrons, which should lead to a n-type conductivity. 19 In any case, the relative symmetry of the experimental results suggests that both electrode interfaces, bottom SRO-BFO and top BFO-Pt, are affected in a similar way by the orientation of the BFO film.…”

Photoconductivity and photo-detection response of multiferroic bismuth iron oxide

“…BFO is known to be an n-type semiconductor at high electric field where a neutral oxygen vacancies can release one or two electrons in the conduction band, 18 and a p-type semiconductor with introduction of Bi vacancies. 19 Here, we established a model of photo-induced decay current that can be derived starting from the continuity equation …”