Publications by authors named "Lemin Jia"

4 Publications

  • Page 1 of 1

High-Pressure O Annealing Enhances the Crystallinity of Ultrawide-Band-Gap Sesquioxides Combined with Graphene for Vacuum-Ultraviolet Photovoltaic Detection.

ACS Appl Mater Interfaces 2021 Apr 31;13(14):16660-16668. Epub 2021 Mar 31.

School of Materials, Sun Yat-sen University, Guangzhou, Guangdong 510275, China.

(AlGa)O is emerging as a promising wide-band-gap sesquioxide for vacuum-ultraviolet (VUV, 10-200 nm) photodetectors and high-power field-effect transistors. However, how the key parameters such as the band gap and crystalline phase of the (AlGa)O-based device vary with stoichiometry has not been explicitly defined, which is due to the unclear underlying mechanism of the Al local coordination environment. In this work, a high-pressure O (20 atm) annealing (HPOA) strategy that can significantly improve the crystallinity of β-(AlGa)O and achieve a tunable optical band gap was proposed, facilitating the revelation of the local structure of Al varying with Al content and the kinetic mechanism of Al diffusion. By combining the as-HPOA-treated single-crystalline β-(AlGa)O films with p-type graphene (p-Gr), which serves as a transparent conductor, a VUV photovoltaic detector is fabricated, showing an improved photovoltage (0.80 V) and fast temporal response (2.1 μs). All of these findings provide a rewarding and important strategy for enhancing the band-gap tunability of sesquioxides, as well as the flexibility of zero-power-consumption photodetectors.
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http://dx.doi.org/10.1021/acsami.1c00429DOI Listing
April 2021

Quasiphonon polaritons.

Heliyon 2020 Oct 23;6(10):e05277. Epub 2020 Oct 23.

State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China.

Mid-infrared reflection spectra of - and -plane bulk AlN show a reststrahlen band related to the formation of phonon polaritons. However, it is worth noting that there are additional hump- and spike-shaped peaks in the spectra, which cannot be explained by the phonon-polaritons model applicable to optically isotropic crystals. Here, considering the existence of quasiphonons in wurtzite crystals, we suppose that the extra peaks result from the generation of quasiphonon polaritons (QPPs) induced by the coupling between photon and quasi-transverse optical phonon. On the basis of this point, a QPPs model applicable to optically anisotropic wurtzite crystals is developed, which successfully explains the reststrahlen band of bulk AlN. Besides, on the ground of our model, a series of reststrahlen band of bulk AlN under various configurations is also predicted and presented.
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http://dx.doi.org/10.1016/j.heliyon.2020.e05277DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7586075PMC
October 2020

Vacuum-Ultraviolet Photon Detections.

iScience 2020 Jun 8;23(6):101145. Epub 2020 May 8.

State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China.

Vacuum-ultraviolet (VUV) photon detection technology is an effective means for the exploration in the field of space science (monitoring the formation and evolution of solar storms), high-energy physics (dark matter detection), large-scale scientific facility (VUV free electron lasers) and electronic industry (high-resolution lithography). The advancement of this technology mainly depends on the performance optimization of VUV photodetectors. In this review, we introduced the research progress on the typical VUV photodetectors based on scintillator, photomultiplier tube, semiconductor, and gas, with their unique advantages and optimal performance indicators in different applications summarized. In particular, during recent years, thanks to the advances in ultra-wide bandgap semiconductors, economical VUV photodetectors with low power consumption and small size have been encouragingly developed. Finally, we pointed out the remaining challenges for each type of VUV detector, with the aim of maximizing the performance in a variety of applications in the future.
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http://dx.doi.org/10.1016/j.isci.2020.101145DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7243193PMC
June 2020

Ultra-high Photovoltage (2.45 V) Forming in Graphene Heterojunction via Quasi-Fermi Level Splitting Enhanced Effect.

iScience 2020 Feb 7;23(2):100818. Epub 2020 Jan 7.

State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials, Sun Yat-sen University, Guangzhou 510275, China.

Owing to the fast response speed and low energy consumption, photovoltaic vacuum-ultraviolet (VUV) photodetectors show prominent advantages in the field of space science, high-energy physics, and electronics industry. For photovoltaic devices, it is imperative to boost their open-circuit voltage, which is the most direct indicator to measure the photoelectric conversion capability. In this report, a quasi-Fermi level splitting enhanced effect under illumination, benefiting from the variable Fermi level of graphene, is proposed to significantly increase the potential difference up to 2.45 V between the two ends of p-Gr/i-AlN/n-SiC heterojunction photovoltaic device. In addition, the highest external quantum efficiency of 56.1% (under the VUV irradiation of 172 nm) at 0 V bias and the ultra-fast photoresponse of 45 ns further demonstrate the superiority of high-open-circuit-voltage devices. The proposed device design strategy and the adopted effect provide a referential way for the construction of various photovoltaic devices.
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http://dx.doi.org/10.1016/j.isci.2020.100818DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6995729PMC
February 2020