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Low-frequency noise in irradiated graphene FETs
摘要： We present a quantitative analysis of the low-frequency noise in irradiated monolayer graphene. In this study, we repeatedly irradiate a back-gated graphene transistor with argon ions at 90 eV and measure its low-frequency noise and channel conductivity after each irradiation. Our results indicate that the noise amplitude decreases monotonically with the increasing density of vacancy defects. The combination of our low-frequency noise measurements and carrier transport studies reveals that the mobility fluctuation model can explain this observation and that the density of vacancy defects, the density of charged impurities, and the mean free path of charge carriers determine the noise amplitude.
关键词： mobility fluctuation model,low-frequency noise,charged impurities,irradiated graphene,vacancy defects,mean free path
更新于2025-09-10 09:29:36
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Floquet topological transition by unpolarized light
摘要： We study Floquet topological transition in irradiated graphene when the polarization of incident light changes randomly with time. We numerically confirm that the noise-averaged time-evolution operator approaches a steady value in the limit of exact Trotter decomposition of the whole period during which incident light has a different polarization at each interval of the decomposition. This steady limit is found to coincide with the time-evolution operator calculated from the noise-averaged Hamiltonian. We observe that at the six corners (Dirac K point) of the hexagonal Brillouin zone of graphene random Gaussian noise strongly modifies the phase band structure induced by circularly polarized light, whereas in the zone center ((cid:2) point) even a strong noise is not able to do the same. This can be understood by analyzing the deterministic noise-averaged Hamiltonian, which has a different Fourier structure as well as a lower number of symmetries compared to the noise-free one. In one-dimensional systems noise is found to renormalize only the drive amplitude.
关键词： unpolarized light,noise-averaged Hamiltonian,Floquet topological transition,irradiated graphene,phase band structure
更新于2025-09-09 09:28:46