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. 2018 Aug 21;8(52):29555-29561.
doi: 10.1039/c8ra05677c. eCollection 2018 Aug 20.

Band offset and an ultra-fast response UV-VIS photodetector in γ-In2Se3/p-Si heterojunction heterostructures

Y X Fang  1 , H Zhang  1 , F Azad  2 , S P Wang  3 , F C C Ling  4 , S C Su  1   4
Affiliations

Band offset and an ultra-fast response UV-VIS photodetector in γ-In2Se3/p-Si heterojunction heterostructures

Y X Fang et al. RSC Adv. .

Abstract

High-quality γ-In2Se3 thin films and a γ-In2Se3/p-Si heterojunction were prepared using pulse laser deposition (PLD). The band offset of this heterojunction was studied by XPS and the band structure was found to be type II structure. The valence band offset (ΔE v) and the conduction band offset (ΔE c) of the heterojunction were determined to be 1.2 ± 0.1 eV and 0.27 ± 0.1 eV, respectively. The γ-In2Se3/p-Si heterojunction photodetector has high responsivity under UV to visible light illumination. The heterojunction exhibits highly stable photodetection characteristics with an ultrafast response/recovery time of 15/366 μs. The ultrafast response time was attributed to type II structure band alignment, which was good for the separation of electron-hole pairs and it can quickly reduce recombination. These excellent properties make γ-In2Se3/p-Si heterojunctions a promising candidate for photodetector applications.

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Conflict of interest statement

There are no conflicts to declare.

Figures

Fig. 1
Fig. 1. The XRD patterns and the Raman spectrum of the In2Se3.
Fig. 2
Fig. 2. (a) The XPS CL spectra of the Zn2p state measured from the Si sample and In2Se3/Si heterojunction, (b) the XPS CL spectra of the Se3d state measured from the In2Se3 films and In2Se3/Si heterojunction, (c) the valence-band XPS spectrum of Si and In2Se3 films, and (d) energy band diagram of type-II band alignment of the In2Se3/Si heterojunction.
Fig. 3
Fig. 3. A typical plots of current voltage characteristics in different metal–semiconductor contacts and In2Se3/Si heterojunction. (Inset: schematic diagram of the γ-In2Se3-ML/Si heterojunction photodetector).
Fig. 4
Fig. 4. Photoelectric characteristics of In2Se3-ML/Si heterojunction in the dark, and their photoresponse at various wavelengths and different illumination intensities: (a) 360, (b) 420, and (c) 500 nm and; (d) photocurrent as a function of light intensity under the reverse bias voltage of −5 V.
Fig. 5
Fig. 5. Optoelectronic performance of In2Se3-ML/Si heterojunction: (a) the seven-cycle time-resolved photoresponse under a bias of −3 V at 365 nm light illumination, (b) a single–period plot of the time-resolved photoresponse, (c) photoresponse of the photodetector at 266 nm laser by a Q-switch Nd:YAG and (d) photoresponse of single period in (c).
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