Electrical and optical properties of low-bandgap oxide Zn2Mo3O8 for optoelectronic applications

THIN SOLID FILMS

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Article

Ravindra, Pramod¹  Baral, Madhusmita³  Biswas, Tathagata⁴  Nand, Mangla³  Jha, S. N.³  Athresh, Eashwer²  Ranjan, Rajeev⁵  Jain, Manish⁴  Ganguli, Tapas³  Avasthi, Sushobhan¹ 

[1] Indian Inst Sci, Ctr Nanosci & Engn, Bangalore 560012, Karnataka, India

[2] Indian Inst Sci, Interdisciplinary Ctr Energy Res, Bangalore 560012, Karnataka, India

[3] Raja Ramanna Ctr Adv Technol, Indore 452013, Madhya Pradesh, India

[4] Indian Inst Sci, Dept Phys, Bangalore 560012, Karnataka, India

[5] Indian Inst Sci, Dept Mat Engn, Bangalore 560012, Karnataka, India

关键词: Oxides;    Photovoltaics;    Semiconductors;    Pulsed laser deposition;   

DOI  :  10.1016/j.tsf.2019.03.023

来源: Elsevier

【 摘 要 】

Semiconducting metal oxides are attractive for various applications since most oxides are non-toxic, stable, and easy to deposit. Wide band-gap materials have been studied more extensively, compared to low bandgap materials, which introduces limitations to the applications of oxides. Study of low band-gap semiconducting oxides can propel the usage of oxides in a wider range of applications. Here, the electronic, structural, and optical properties of Zn2Mo3O8 (ZMO) are investigated. Stoichiometric polycrystalline films of ZMO are deposited using pulsed laser deposition system at room temperature. The unintentionally n-doped films show a hall electron mobility of 0.7 cm(2)V(-1) s(-1) and have a bandgap of 2.1 eV. The photoelectron spectra contain complex peak profiles which are explained to be a manifestation of final state effects. The orbital contribution to the valence band of ZMO is probed using resonant photoelectron spectroscopy, which confirms that the valence band is composed of Mo 4d levels. The conduction and valence band edges are predicted to be at 4.2 eV and 6.3 eV, so most of the conventional wide band-gap oxides can be used as hole-blocking layers with ZMO. Under A.M. 1.5 illumination, single-sided Schottky diode with Fluorine-doped fin oxide/TiO2/ZMO/Au structure shows no photovoltaic action, possibly due to high exciton binding energy and low carrier drift lengths. However, the Schottky device shows a higher current under illumination, which suggests that with improvement in carrier drift lengths, ZMO can find applications in low-cost optoelectronic devices on flexible substrates like plastic or Polyethylene terephthalate.

【 授权许可】

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