科研之友
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摘要
A computationally efficient modelling approach for the study of the small-signal and high-frequency noise properties of graphene is presented. The method combines stationary Monte Carlo particle simulations and analytical balance equations. Relevant parameters, like energy and velocity relaxation rates, are determined as a function of the applied electric field for graphene on several substrates of interest. The results show that transport in graphene is characterized by a streaming motion regime governed by the interplay between the applied field and the interactions with surface polar phonons. The dynamic behavior is analyzed by means of the response matrix, the time dependent velocity response functions, and the spectra and cut-off frequency of the differential mobility. It is shown that the negative differential mobility intrinsic of pure graphene could be exploited up to the THz in graphene on h-BN, SiC, SiO2, and even HfO2, with values approaching those of III-V nitrides, thus opening the possibility of graphene-based frequency multipliers, fast switches, or high frequency oscillators based on this effect. The correlation functions of velocity fluctuations and their power spectral density are also computed in order to determine the noise temperature, which shows a good agreement with complete Monte Carlo simulations, thus assuring the reliability of the proposed approach. Published by AIP Publishing.
- 出版日期2017-5-14
