Searching for new carbon allotropes with superior properties has been a longstanding interest in material sciences and condensed matter physics.Here we identify a novel superhard carbon phase with an 18-atom trigonal ...Searching for new carbon allotropes with superior properties has been a longstanding interest in material sciences and condensed matter physics.Here we identify a novel superhard carbon phase with an 18-atom trigonal unit cell in a full-sp^(3) bonding network,termed tri-C_(18) carbon,by first-principles calculations.Its structural stability has been verified by total energy,phonon spectra,elastic constants,and molecular dynamics simulations.Furthermore,tri-C_(18) carbon has a high bulk modulus of 400 GPa and Vickers hardness of 79.0 GPa,comparable to those of diamond.Meanwhile,the simulated x-ray diffraction pattern of tri-C_(18) carbon matches well with the previously unexplained diffraction peaks found in chimney soot,indicating the possible presence of tri-C_(18) carbon.Remarkably,electronic band structure calculations reveal that tri-C_(18) carbon has a wide indirect bandgap of 6.32 eV,larger than that of cubic diamond,indicating its great potential in electronic or optoelectronic devices working in the deep ultraviolet region.展开更多
We report observation of dispersion for coupled exciton-polariton in a plate microcavity combining with ZnO/MgZnO multi-quantum well (QW) at room temperature. Benefited from the large exciton binding energy and giant ...We report observation of dispersion for coupled exciton-polariton in a plate microcavity combining with ZnO/MgZnO multi-quantum well (QW) at room temperature. Benefited from the large exciton binding energy and giant oscillator strength, the room-temperature Rabi splitting energy can be enhanced to be as large as 60 meV. The results of excitonic polariton dispersion can be well described using the coupling wave model. It is demonstrated that mode modification between polariton branches allowing, just by controlling the pumping location, to tune the photonic fraction in the different detuning can be investigated comprehensively. Our results present a direct observation of the exciton-polariton dispersions based on two-dimensional oxide semiconductor quantum wells, thus provide a feasible road for coupling of exciton with photon and pave the way for realizing novel polariton-type optoelectronic devices.展开更多
基金Supported by the National Natural Science Foundation of China(Grant Nos.11804307,U1804155,and U1604263)the China Postdoctoral Science Foundation(Grant Nos.2018M630830 and 2019T120631).
文摘Searching for new carbon allotropes with superior properties has been a longstanding interest in material sciences and condensed matter physics.Here we identify a novel superhard carbon phase with an 18-atom trigonal unit cell in a full-sp^(3) bonding network,termed tri-C_(18) carbon,by first-principles calculations.Its structural stability has been verified by total energy,phonon spectra,elastic constants,and molecular dynamics simulations.Furthermore,tri-C_(18) carbon has a high bulk modulus of 400 GPa and Vickers hardness of 79.0 GPa,comparable to those of diamond.Meanwhile,the simulated x-ray diffraction pattern of tri-C_(18) carbon matches well with the previously unexplained diffraction peaks found in chimney soot,indicating the possible presence of tri-C_(18) carbon.Remarkably,electronic band structure calculations reveal that tri-C_(18) carbon has a wide indirect bandgap of 6.32 eV,larger than that of cubic diamond,indicating its great potential in electronic or optoelectronic devices working in the deep ultraviolet region.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974433,91833301,and 11974122)the Guangdong Natural Science Fund for Distinguished Young Scholars,China(Grant No.2016A030306044)the Science and Technology Program of Guangzhou,China(Grant No.201707020014).
文摘We report observation of dispersion for coupled exciton-polariton in a plate microcavity combining with ZnO/MgZnO multi-quantum well (QW) at room temperature. Benefited from the large exciton binding energy and giant oscillator strength, the room-temperature Rabi splitting energy can be enhanced to be as large as 60 meV. The results of excitonic polariton dispersion can be well described using the coupling wave model. It is demonstrated that mode modification between polariton branches allowing, just by controlling the pumping location, to tune the photonic fraction in the different detuning can be investigated comprehensively. Our results present a direct observation of the exciton-polariton dispersions based on two-dimensional oxide semiconductor quantum wells, thus provide a feasible road for coupling of exciton with photon and pave the way for realizing novel polariton-type optoelectronic devices.
