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Modulation of the Bi3+ 6s2 Lone Pair State in Perovskites for High-Mobility p-Type Oxide Semiconductors.

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Shi, Jueli 
Rubinstein, Ethan A 
Li, Weiwei 
Zhang, Jiaye 
Yang, Ye 


Oxide semiconductors are key materials in many technologies from flat-panel displays,solar cells to transparent electronics. However, many potential applications are hindered by the lack of high mobility p-type oxide semiconductors due to the localized O-2p derived valence band (VB) structure. In this work, the VB structure modulation is reported for perovskite Ba2 BiMO6 (M = Bi, Nb, Ta) via the Bi 6s2 lone pair state to achieve p-type oxide semiconductors with high hole mobility up to 21 cm2 V-1 s-1 , and optical bandgaps widely varying from 1.5 to 3.2 eV. Pulsed laser deposition is used to grow high quality epitaxial thin films. Synergistic combination of hard x-ray photoemission, x-ray absorption spectroscopies, and density functional theory calculations are used to gain insight into the electronic structure of Ba2 BiMO6 . The high mobility is attributed to the highly dispersive VB edges contributed from the strong coupling of Bi 6s with O 2p at the top of VB that lead to low hole effective masses (0.4-0.7 me ). Large variation in bandgaps results from the change in the energy positions of unoccupied Bi 6s orbital or Nb/Ta d orbitals that form the bottom of conduction band. P-N junction diode constructed with p-type Ba2 BiTaO6 and n-type Nb doped SrTiO3 exhibits high rectifying ratio of 1.3 × 104 at ±3 V, showing great potential in fabricating high-quality devices. This work provides deep insight into the electronic structure of Bi3+ based perovskites and guides the development of new p-type oxide semiconductors.


Funder: Collaborative Innovation Center of Chemistry for Energy Materials; Id:

Funder: Top‐notch Academic Programs Project of Jiangsu Higher Education Institutions


DFT calculations, electronic structures, p-type oxide semiconductors, photoemission spectroscopy

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Adv Sci (Weinh)

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National Natural Science Foundation of China (21872116, 22075232)
EPSRC (EP/L000202, EP/R029431)
UK Materials and Molecular Modelling (EP/P020194)
EPSRC (EP/L011700/1, EP/N004272/1, EP/P027032/1)
Royal Academy of Engineering Chair in Emerging Technologies (CiET1819∖24)
National Natural Science Foundation of China (52102177)
National Natural Science Foundation of Jiangsu Province (BK20210313)