Mihaila M, Ursutiu D, Sandu I
National Institute of Research and Development in Microtechnologies-IMT Bucharest, Erou Iancu Nicolae str. 126A, 077190, Bucharest, Romania.
University Transilvania - Brasov, Department of Electrical Engineering and Computer Science, Oltenia str. 2A, 500209, Brasov, Romania.
Sci Rep. 2019 Jan 30;9(1):947. doi: 10.1038/s41598-018-36544-4.
Two 1/f noise peaks were found in a carbon soot resistor at voltages characteristic of Kohn anomalies in graphite. The ratio of the electron-phonon coupling matrix elements at the anomalies calculated from the noise peak intensities is the same as the one obtained from the Raman frequencies. This demonstrates that the electron-phonon coupling is the microscopic source of 1/f noise in carbon soot. A new, very general formula was deduced for the frequency exponent, wherein nonlinearity and dispersion are the only ingredients. The interplay between nonlinearity and dispersion in this formula describes the sublinear-supralinear transitions experimentally observed at both anomalies in the voltage dependence of the frequency exponent. A quadratic dependence of the 1/f noise parameter on the matrix element is proposed and applied to explain the M-shape of the 1/f noise in graphene. We found that the frequency exponent mimics the dependence of the noise intensity in the whole voltage range, while both are the image of the graphite phonon spectrum. This implies that the source of nonlinearity is in the electron-phonon coupling which modulates the slope of the spectrum. It requires the presence of 1/f noise in the thermal noise background of the resistor till phonon frequencies.
在碳黑电阻器中，于石墨中Kohn反常现象的特征电压处发现了两个1/f噪声峰。根据噪声峰强度计算得出的反常现象处的电子 - 声子耦合矩阵元之比，与从拉曼频率获得的结果相同。这表明电子 - 声子耦合是碳黑中1/f噪声的微观来源。推导了一个新的、非常通用的频率指数公式，其中非线性和色散是唯一的要素。该公式中非线性和色散之间的相互作用描述了在频率指数的电压依赖性中两个反常现象处实验观察到的亚线性 - 超线性转变。提出了1/f噪声参数对矩阵元的二次依赖性，并用于解释石墨烯中1/f噪声的M形。我们发现频率指数在整个电压范围内模拟噪声强度的依赖性，而两者都是石墨声子谱的反映。这意味着非线性的来源在于调制谱斜率的电子 - 声子耦合。这要求在电阻器直至声子频率的热噪声背景中存在1/f噪声。
