A broad-spectrum UV photodetector with ultrahigh detectivity and rapid response speed has been achieved inβ-Ga_(2)O_(3)/GaN heterojunction,in which,theβ-Ga_(2)O_(3) is synthesized by substituting oxygen for nitrogen...A broad-spectrum UV photodetector with ultrahigh detectivity and rapid response speed has been achieved inβ-Ga_(2)O_(3)/GaN heterojunction,in which,theβ-Ga_(2)O_(3) is synthesized by substituting oxygen for nitrogen in the top layer of the GaN matrix at high temperature.The processes and mechanism of transforming GaN with varying crystal quality into β-Ga_(2)O_(3) at high temperatures were studied in detail.The newly formed oxide layer is a monoclinic β-Ga_(2)O_(3) with(01)preferred orientation.X-ray photoelectron spectroscopy(XPS)and atomic force microscope(AFM)measurements identified oxygen vacancies and surface flatness of β-Ga_(2)O_(3),respectively,which are closely related to the crystal quality of GaN.The oxygen vacancies and the root mean square of morphology roughness of β-Ga_(2)O_(3) decrease with the improvement of the precursor GaN crystal quality.The cross-section transmission electron microscope(TEM)measurements showed that a hexagonal phase GaN_(x)O_(3(1−x)/2)intermediate layer with a thickness of 5 nm exists at the interface region betweenβ-Ga_(2)O_(3) and hexagonal GaN.This indicates a molecular reconfiguration of the hexagonal system to a monoclinic system with oxygen substitution of nitrogen in GaN matrix.The metal-semiconductor-metal(MSM)planar structure device achieved an ultrahigh detection capability(Responsivity=2493.5 A/W,Detectivity>10^(16)Jones).The response time is in the order of milliseconds(τ_(r)=0.27 ms,τ_(d1)/τ_(d2)=0.33 ms/4.3 ms).A self-powered UV optoelectronic rapid response(τ_(r)=5µs,τ_(d1)/τ_(d2)=0.13 ms/2.3 ms)with the responsivity of 0.6 mA/W and the detectivity of 5.3×10^(11)Jones in the solar-blind wavelength region has been observed in the β-Ga_(2)O_(3)/GaN heterojunction without external bias.With a bias of−10 V loading,the response of the photodetector becomes a broad spectrum,covering the UVA-UVC wavelength range,and the photoresponsivity is up to 13.5 A/W.The detectivity reaches a high value of 2.6×10^(15)Jones.展开更多
Ultrawide band gap semiconductors are promising solar-blind ultraviolet(UV)photodetector materials due to their suitable bandgap,strong absorption and high sensitivity.Here,β-Ga_(2)O_(3)microwires with high crystal q...Ultrawide band gap semiconductors are promising solar-blind ultraviolet(UV)photodetector materials due to their suitable bandgap,strong absorption and high sensitivity.Here,β-Ga_(2)O_(3)microwires with high crystal quality and large size were grown by the chemical vapor deposition(CVD)method.The microwires reach up to 1 cm in length and were single crystalline with low defect density.Owing to its high crystal quality,a metal–semiconductor–metal photodetector fabricated from a Ga_(2)O_(3)microwire showed a responsivity of 1.2 A/W at 240 nm with an ultrahigh UV/visible rejection ratio(R_(peak)/R_(400 nm))of 5.8×10^(5),indicating that the device has excellent spectral selectivity.In addition,no obvious persistent photoconductivity was observed in the test.The rise and decay time constants of the device were 0.13 and 0.14 s,respectively.This work not only provides a growth method for high-quality Ga_(2)O_(3)microwires,but also demonstrates the excellent performance of Ga_(2)O_(3)microwires in solar-blind ultraviolet detection.展开更多
Single-atom nanozymes(SAzymes)are emerging as promising alternatives to mimic natural enzyme,which is due to high atomic utilization efficiency,well-defined geometric,and unique electronic structure.Herein,Fe single a...Single-atom nanozymes(SAzymes)are emerging as promising alternatives to mimic natural enzyme,which is due to high atomic utilization efficiency,well-defined geometric,and unique electronic structure.Herein,Fe single atoms supported on Ti_(3)C_(2)T_(x)(Fe-SA/Ti_(3)C_(2)T_(x))with intrinsic peroxidase activity is developed,further constructing a sensitive Raman sensor array for sensing of five antioxidants.Fe-SA/Ti_(3)C_(2)T_(x)shows excellent peroxidase-like performance in catalyzing the oxidation of 3,3',5,5'-tetramethylbenzidine(TMB)with colorimetric reactions.X-ray adsorption fine structure(XAFS)reveals that the electron transport between the Ti_(3)C_(2)T_(x)and Fe atoms occurs along Fe-O-Ti ligands,meanwhile the density functional theory(DFT)calculations confirm the spontaneous dissociation of H_(2)O_(2)and the formation of OH radicals.Furthermore,the peroxidase-like Fe-SA/Ti_(3)C_(2)T_(x)was used as surface enhanced Raman scattering(SERS)substrate of oxidized TMB(TMB+)and achieved satisfied signal amplification performance.Using the blocking effects of free radical reactions,one-off identification of 5 antioxidants,including ascorbic acid(AA),uric acid(UA),glutathione(GSH),melatonin(Mel),and tea polyphenols(TPP),could be realized with this high identifiable catalytic property.This principle could realize 100%distinguish accuracy combined with linear discriminant analysis(LDA)and heat map data analysis.A wide detection concentration ranges from 10^(-8)to 10^(-3)M for five antioxidants was also achieved.展开更多
基金financially supported by National Key Technologies Research and Development Program of China(No.2019YFA0705202)National Natural Science Foundation of China(Nos.62274027,62404039)+3 种基金Open Research Fund of Songshan Lake Materials Laboratory(No.2023SLABFK03)Funding from Jilin Province(No.20220502002GH)Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(No.GZC20230416)Fundamental Research Funds for the Central Universities(No.2412024QD010).
文摘A broad-spectrum UV photodetector with ultrahigh detectivity and rapid response speed has been achieved inβ-Ga_(2)O_(3)/GaN heterojunction,in which,theβ-Ga_(2)O_(3) is synthesized by substituting oxygen for nitrogen in the top layer of the GaN matrix at high temperature.The processes and mechanism of transforming GaN with varying crystal quality into β-Ga_(2)O_(3) at high temperatures were studied in detail.The newly formed oxide layer is a monoclinic β-Ga_(2)O_(3) with(01)preferred orientation.X-ray photoelectron spectroscopy(XPS)and atomic force microscope(AFM)measurements identified oxygen vacancies and surface flatness of β-Ga_(2)O_(3),respectively,which are closely related to the crystal quality of GaN.The oxygen vacancies and the root mean square of morphology roughness of β-Ga_(2)O_(3) decrease with the improvement of the precursor GaN crystal quality.The cross-section transmission electron microscope(TEM)measurements showed that a hexagonal phase GaN_(x)O_(3(1−x)/2)intermediate layer with a thickness of 5 nm exists at the interface region betweenβ-Ga_(2)O_(3) and hexagonal GaN.This indicates a molecular reconfiguration of the hexagonal system to a monoclinic system with oxygen substitution of nitrogen in GaN matrix.The metal-semiconductor-metal(MSM)planar structure device achieved an ultrahigh detection capability(Responsivity=2493.5 A/W,Detectivity>10^(16)Jones).The response time is in the order of milliseconds(τ_(r)=0.27 ms,τ_(d1)/τ_(d2)=0.33 ms/4.3 ms).A self-powered UV optoelectronic rapid response(τ_(r)=5µs,τ_(d1)/τ_(d2)=0.13 ms/2.3 ms)with the responsivity of 0.6 mA/W and the detectivity of 5.3×10^(11)Jones in the solar-blind wavelength region has been observed in the β-Ga_(2)O_(3)/GaN heterojunction without external bias.With a bias of−10 V loading,the response of the photodetector becomes a broad spectrum,covering the UVA-UVC wavelength range,and the photoresponsivity is up to 13.5 A/W.The detectivity reaches a high value of 2.6×10^(15)Jones.
基金supported by the National Key R&D Program of China(Grant No.2019YFA0705202)the National Natural Science Foundation of China(Grant Nos.62274027 and 31701296)。
文摘Ultrawide band gap semiconductors are promising solar-blind ultraviolet(UV)photodetector materials due to their suitable bandgap,strong absorption and high sensitivity.Here,β-Ga_(2)O_(3)microwires with high crystal quality and large size were grown by the chemical vapor deposition(CVD)method.The microwires reach up to 1 cm in length and were single crystalline with low defect density.Owing to its high crystal quality,a metal–semiconductor–metal photodetector fabricated from a Ga_(2)O_(3)microwire showed a responsivity of 1.2 A/W at 240 nm with an ultrahigh UV/visible rejection ratio(R_(peak)/R_(400 nm))of 5.8×10^(5),indicating that the device has excellent spectral selectivity.In addition,no obvious persistent photoconductivity was observed in the test.The rise and decay time constants of the device were 0.13 and 0.14 s,respectively.This work not only provides a growth method for high-quality Ga_(2)O_(3)microwires,but also demonstrates the excellent performance of Ga_(2)O_(3)microwires in solar-blind ultraviolet detection.
基金This work was supported by the National Natural Science Foundation of China(Nos.51872011,51902011,and 22005013)Beijing Natural Science Foundation(No.2212018)+1 种基金Beijing Institute of Technology Research Fund Program for Young Scholars(No.2022CX01011)Chinese Academy of Sciences。
文摘Single-atom nanozymes(SAzymes)are emerging as promising alternatives to mimic natural enzyme,which is due to high atomic utilization efficiency,well-defined geometric,and unique electronic structure.Herein,Fe single atoms supported on Ti_(3)C_(2)T_(x)(Fe-SA/Ti_(3)C_(2)T_(x))with intrinsic peroxidase activity is developed,further constructing a sensitive Raman sensor array for sensing of five antioxidants.Fe-SA/Ti_(3)C_(2)T_(x)shows excellent peroxidase-like performance in catalyzing the oxidation of 3,3',5,5'-tetramethylbenzidine(TMB)with colorimetric reactions.X-ray adsorption fine structure(XAFS)reveals that the electron transport between the Ti_(3)C_(2)T_(x)and Fe atoms occurs along Fe-O-Ti ligands,meanwhile the density functional theory(DFT)calculations confirm the spontaneous dissociation of H_(2)O_(2)and the formation of OH radicals.Furthermore,the peroxidase-like Fe-SA/Ti_(3)C_(2)T_(x)was used as surface enhanced Raman scattering(SERS)substrate of oxidized TMB(TMB+)and achieved satisfied signal amplification performance.Using the blocking effects of free radical reactions,one-off identification of 5 antioxidants,including ascorbic acid(AA),uric acid(UA),glutathione(GSH),melatonin(Mel),and tea polyphenols(TPP),could be realized with this high identifiable catalytic property.This principle could realize 100%distinguish accuracy combined with linear discriminant analysis(LDA)and heat map data analysis.A wide detection concentration ranges from 10^(-8)to 10^(-3)M for five antioxidants was also achieved.
