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Photovoltaic and flexible deep ultraviolet wavelength detector based on novel ?-Ga₂O₃/muscovite heteroepitaxy.

ABSTRACT: Flexible and self-powered deep ultraviolet (UV) photodetectors are pivotal for next-generation electronic skins to enrich human life quality. The fabrication of epitaxial ?-Ga₂O₃ thin films is challenging on flexible substrates due to high-temperature growth requirements. Herein, ?-Ga₂O₃ ([Formula: see text] 0 1) films are hetero-epitaxially grown on ultra-thin and environment-friendly muscovite mica which is the first time ?-Ga₂O₃ epitaxy growth on any flexible substrate. Integration of Gallium oxide with muscovite enables high-temperature processing as well as excellent flexibility compared to polymer substrates. Additionally, the metal-semiconductor-metal (MSM) photodetector on ?-Ga₂O₃ layer shows an ultra-low dark current of 800 fA at zero bias. The photovoltaic peak responsivity of 11.6 µA/W is obtained corresponding to very weak illumination of 75 ?W/cm² of 265 nm wavelength. Thermally stimulated current (TSC) measurements are employed to investigate the optically active trap states. Among these traps, trap with an activation energy of 166 meV dominates the persistence photocurrent in the devices. Finally, photovoltaic detectors have shown excellent photocurrent stability under bending induced stress up to 0.32%. Hence, this novel heteroepitaxy opens the new way for flexible deep UV photodetectors.

SUBMITTER: Tak BR

PROVIDER: S-EPMC7528161 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Photovoltaic and flexible deep ultraviolet wavelength detector based on novel β-Ga2O3/muscovite heteroepitaxy.

Tak Bhera Ram BR Yang Ming-Min MM Lai Yu-Hong YH Chu Ying-Hao YH Alexe Marin M Singh Rajendra R

Scientific reports 20200930 1

Flexible and self-powered deep ultraviolet (UV) photodetectors are pivotal for next-generation electronic skins to enrich human life quality. The fabrication of epitaxial β-Ga2O3 thin films is challenging on flexible substrates due to high-temperature growth requirements. Herein, β-Ga2O3 ([Formula: see text] 0 1) films are hetero-epitaxially grown on ultra-thin and environment-friendly muscovite mica which is the first time β-Ga2O3</sub ...[more]

PMID: 32999335

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Project description:It is generally known that a layer of amorphous silicon oxide (SiO2) naturally exists on the surface of silicon, resulting in the growth of gallium oxide (Ga2O3) that is no longer affected by substrate crystallinity during sputtering. This work highlights the formation energy between the native amorphous nano-oxide film formed on the Si substrate and monoclinic β-Ga2O3 dominating the preferred orientation prepared for deep ultraviolet photodetectors. The latter were deposited on p-type silicon (p-Si) with (111) orientation using radio frequency sputtering at 600 °C and post rapid thermal annealing (RTA). The X-ray diffraction (XRD) results indicate both as-deposited and postannealing films with the (400) preferred orientation for a layer thickness of 100 nm. However, slight random orientation with the amorphous structure is mixed in the preferred one for the as-deposited film with a thickness of 200 nm and reduced after being annealed at 800 °C, which is observed by XRD and transmission electron microscopy. Meanwhile, thermal-induced massive twin boundaries (TBs) and stacking faults (SFs) were generated when annealed at 1000 °C, owing to the relaxation of lattice strain by the coherent interface. The interfacial bonding energy per unit area (E i) between β-Ga2O3 films with various facets ((001), (010), (100), and (2̅01)) and amorphous SiO2 was calculated using density functional theory. The E i of β-Ga2O3 (100)/SiO2 reveals the highest value (0.289 eV/Å2), which is consistent with the (100) preferred orientation of deposited films. The (100) preferred orientation is the driving force for TBs and SFs. The discrimination of responsivities and the photo/dark current contrast ratio (I ph/I dark) are inversely proportional to the amorphous structure, grain boundaries, TBs, and SFs. Therefore, optimum metal-semiconductor-metal photodetector performance is achieved for RTA-treated samples at 800 °C with an I ph/I dark of 3.91 × 102 and a responsivity of 0.702 A/W (λpeak = 230 nm) at 5 V bias for a 200 nm thin film.

Project description:TiO2 nanoparticles surface-modified with silane moieties, which can be directly coated on a flexible substrate without the requirement of any binder materials and postsintering processes, are synthesized and characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy, Raman spectroscopy, photoluminescence spectroscopy, time-correlated single-photon counting, and transmission electron microscopy. The viability of the prepared surface-modified TiO2 (M-TiO2) sheets as a catalyst for the photo-induced degradation of a model dye, methylene blue, was checked using UV-visible absorption spectroscopy. The data suggest that, compared to unmodified TiO2, M-TiO2 sheets facilitate better dye-degradation, which leads to a remarkable photocatalytic activity that results in more than 95% degradation of the dye in the first 10 min and more than 99% of the degradation in the first 50 min of the photocatalytic experiments. We also demonstrate that M-TiO2 can be recycled with negligible reduction in photocatalytic activity. Further, the photovoltaic properties of the developed M-TiO2 sheets were assessed using UV-visible absorption spectroscopy, electrochemical impedance spectroscopy (EIS), and photochronoamperometry. Dye-sensitized solar cells (DSSC) fabricated using M-TiO2 as the photoanode exhibited a photoconversion efficiency of 4.1% under direct sunlight. These experiments suggested that M-TiO2 sheets show enhanced photovoltaic properties compared to unmodified TiO2 sheets, and that, when N-719 dye is incorporated, the dye-TiO2 interaction is more favorable for M-TiO2 than bare TiO2. The simple solution processing method demonstrated in this paper rendered a highly flexible photoanode made of M-TiO2 with superior charge-separation efficiency to an electrode made of bare TiO2. We propose that our findings on the photovoltaic properties of M-TiO2 open up arenas of further improvement and a wide scope for the large-scale production of flexible DSSCs on plastic substrates at room temperature in a cost-effective way.

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Photovoltaic and flexible deep ultraviolet wavelength detector based on novel ?-Ga₂O₃/muscovite heteroepitaxy.

Publications

Photovoltaic and flexible deep ultraviolet wavelength detector based on novel β-Ga<sub>2</sub>O<sub>3</sub>/muscovite heteroepitaxy.

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OmicsDI is part of the ELIXIR infrastructure

Dataset Information

Photovoltaic and flexible deep ultraviolet wavelength detector based on novel ?-Ga2O3/muscovite heteroepitaxy.

Publications

Photovoltaic and flexible deep ultraviolet wavelength detector based on novel β-Ga<sub>2</sub>O<sub>3</sub>/muscovite heteroepitaxy.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Photovoltaic and flexible deep ultraviolet wavelength detector based on novel ?-Ga₂O₃/muscovite heteroepitaxy.