Here we present a graphene photodetector ofwhich the graphene and structural system infraredabsorptions are enhanced by interface phonon polariton(IPhP) coupling. IPhPs are supported at the SiC/AlNinterface of device ...Here we present a graphene photodetector ofwhich the graphene and structural system infraredabsorptions are enhanced by interface phonon polariton(IPhP) coupling. IPhPs are supported at the SiC/AlNinterface of device structure and used to excite interbandtransitions of the intrinsic graphene under gated-fieldtuning. The simulation results show that at normalincidence the absorbance of graphene or system reachesup to 43% or closes to unity in a mid-infrared frequencyrange. In addition, we found the peak-absorption frequencyis mainly decided by the AlN thickness, and it has ared-shift as the thickness decreases. This structure has greatapplication potential in graphene infrared detectiontechnology.展开更多
The polar interface optical (IO) and surface optical (SO) phonon modes and the corresponding Froehlich electron phonon-interaction Hamiltonian in a freestanding multi-layer wurtzite cylindrical quantum wire (QWR...The polar interface optical (IO) and surface optical (SO) phonon modes and the corresponding Froehlich electron phonon-interaction Hamiltonian in a freestanding multi-layer wurtzite cylindrical quantum wire (QWR) are derived and studied by employing the transfer matrix method in the dielectric continuum approximation and Loudon's uniaxial crystal model. A numerical calculation of a freestanding wurtzite GaN/AlN QWR is performed. The results reveal that for a relatively large azimuthal quantum number m or wave-number kz in the free z-direction, there exist two branches of IO phonon modes localized at the interface, and only one branch of SO mode localized at the surface in the system. The degenerating behaviours of the IO and SO phonon modes in the wurtzite QWR have also been clearly observed for a small kz or m. The limiting frequency properties of the IO and SO modes for large kz and m have been explained reasonably from the mathematical and physical viewpoints. The calculations of electron-phonon coupling functions show that the high-frequency IO phonon branch and SO mode play a more important role in the electron phonon interaction.展开更多
In this work,we report that the thermoelectric properties of Bi(0.52)Sb(1.48)Te3alloy can be enhanced by being composited with Mn Te nano particles(NPs)through a combined ball milling and spark plasma sintering...In this work,we report that the thermoelectric properties of Bi(0.52)Sb(1.48)Te3alloy can be enhanced by being composited with Mn Te nano particles(NPs)through a combined ball milling and spark plasma sintering(SPS)process.The addition of Mn Te into the host can synergistically reduce the lattice thermal conductivity by increasing the interface phononscattering between Bi(0.52)Sb(1.48)Te3 and MnTe NPs,and enhance the electrical transport properties by optimizing the hole concentration through partial Mn^2+ acceptor doping on the Bi^3+ sites of the host lattice.It is observed that the lattice thermal conductivity decreases with increasing the percentage of Mn Te and milling time in a temperature range from 300 Kto 500 K,which is consistent with the increasing of interfaces.Meanwhile,the bipolar effect is constrained to high temperatures,which results in the figure of merit z T peak shifting toward higher temperature and broadening the z T curves.The engineering z T is obtained to be 20%higher than that of the pristine sample for the 2-mol%Mn Te-added composite at a temperature gradient of 200 K when the cold end temperature is set to be 300 K.This result indicates that the thermoelectric performance of Bi0.52Sb1.48Te3 can be considerably enhanced by being composited with Mn Te NPs.展开更多
基金the National NaturalScience Foundation of China (NSFC) (Grant No. 61675080)FundamentalResearch Funds for the Central Universities (HUST: 2016YXMS021).
文摘Here we present a graphene photodetector ofwhich the graphene and structural system infraredabsorptions are enhanced by interface phonon polariton(IPhP) coupling. IPhPs are supported at the SiC/AlNinterface of device structure and used to excite interbandtransitions of the intrinsic graphene under gated-fieldtuning. The simulation results show that at normalincidence the absorbance of graphene or system reachesup to 43% or closes to unity in a mid-infrared frequencyrange. In addition, we found the peak-absorption frequencyis mainly decided by the AlN thickness, and it has ared-shift as the thickness decreases. This structure has greatapplication potential in graphene infrared detectiontechnology.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60276004 and 60390073) and the Natural Science Foundation of Guangzhou Education Bureau, China (Grant No 2060). Acknowledgement The author would like to thank Professor J J Shi for detailed and valuable discussion.
文摘The polar interface optical (IO) and surface optical (SO) phonon modes and the corresponding Froehlich electron phonon-interaction Hamiltonian in a freestanding multi-layer wurtzite cylindrical quantum wire (QWR) are derived and studied by employing the transfer matrix method in the dielectric continuum approximation and Loudon's uniaxial crystal model. A numerical calculation of a freestanding wurtzite GaN/AlN QWR is performed. The results reveal that for a relatively large azimuthal quantum number m or wave-number kz in the free z-direction, there exist two branches of IO phonon modes localized at the interface, and only one branch of SO mode localized at the surface in the system. The degenerating behaviours of the IO and SO phonon modes in the wurtzite QWR have also been clearly observed for a small kz or m. The limiting frequency properties of the IO and SO modes for large kz and m have been explained reasonably from the mathematical and physical viewpoints. The calculations of electron-phonon coupling functions show that the high-frequency IO phonon branch and SO mode play a more important role in the electron phonon interaction.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1601213 and 51472052)the Funds from Institute of Physics,Chinese Academy of Sciences
文摘In this work,we report that the thermoelectric properties of Bi(0.52)Sb(1.48)Te3alloy can be enhanced by being composited with Mn Te nano particles(NPs)through a combined ball milling and spark plasma sintering(SPS)process.The addition of Mn Te into the host can synergistically reduce the lattice thermal conductivity by increasing the interface phononscattering between Bi(0.52)Sb(1.48)Te3 and MnTe NPs,and enhance the electrical transport properties by optimizing the hole concentration through partial Mn^2+ acceptor doping on the Bi^3+ sites of the host lattice.It is observed that the lattice thermal conductivity decreases with increasing the percentage of Mn Te and milling time in a temperature range from 300 Kto 500 K,which is consistent with the increasing of interfaces.Meanwhile,the bipolar effect is constrained to high temperatures,which results in the figure of merit z T peak shifting toward higher temperature and broadening the z T curves.The engineering z T is obtained to be 20%higher than that of the pristine sample for the 2-mol%Mn Te-added composite at a temperature gradient of 200 K when the cold end temperature is set to be 300 K.This result indicates that the thermoelectric performance of Bi0.52Sb1.48Te3 can be considerably enhanced by being composited with Mn Te NPs.