Noise in Graphene Superlattices Grown on Hexagonal Boron Nitride

Abstract

Existing in almost all electronic systems, the current noise spectral density, originated from the fluctuation of current, is by nature far more sensitive than the mean value of current, the most common characteristic parameter in electronic devices. Existing models on its origin of either carrier number or mobility are adopted in practically all electronic devices. For the past few decades, there has been no experimental evidence for direct association between 1/f noise and any other kinetic phenomena in solid state devices. Here, in the study of a van der Waals heterostructure of graphene on hexagonal BN superlattice, satellite Dirac points have been characterized through 1/f noise spectral density with pronounced local minima and asymmetric magnitude associated with its unique energy dispersion spectrum, which can only be revealed by scanning tunneling microscopy and low temperature magneto-transport measurement. More importantly, these features even emerge in the noise spectra of devices showing no minima in electric current, and are robust at all temperatures down to 4.3 K. In addition, graphene on h-BN exhibits a record low noise level of 1.6 × 10(-9) μm(2) Hz(-1) at 10 Hz, more than 1 order of magnitude lower than previous results for graphene on SiO2. Such an epitaxial van der Waals material system not only enables an unprecedented characterization of fundamentals in solids by 1/f noise, but its superior interface also provides a key and feasible solution for further improvement of the noise level for graphene devices.

Growth of Graphene/h-BN Heterostructures on Recyclable Pt Foils by One-Batch Chemical Vapor Deposition

“…Therefore, h-BN film is considered an ideal substrate to synthesize high-quality graphene. It should be noted that the mobility values observed in our devices are 2 to 3 times higher than those reported elsewhere for LPCVD grown graphene on h-BN film 31 , 32 . Moreover, the histogram of the carrier mobility values and the average V dirac for up to 60 devices, shown in Fig.…”

Graphene on h-BN: to align or not to align?

“…Simulated moiré patterns of graphene Experimentally, moiré patterns with a length of approximately 14 nm have been reported, [9,14,15] consistent with perfect alignment, θ = 0…”

“…1: ∆z 40 pm vs. ∆z exp 35 pm). [9,16] As it turned out, the two crucial elements that influenced alignment or misalignment were graphene corrugation and in-plane deformability of h-BN. To understand the role of out-ofplane motion of graphene, easily permitted by its soft ZA modes, we repeated all calculations by imposing a solidal motion of graphene atoms in the out-of-plane direction, which blocked corrugations.…”

“…[7] As of now however, a sharp assessment of the equilibrium alignment or misalignment and of the friction of graphene on pertinent substrates, such as h-BN, Cu, and others, is missing. Existing experimental work with h-BN deposited graphene [8][9][10] is abundant, and a variety of observed deposition angles are reported. Generally, it appears that the deposition history and kinetics dominates the relative angle much more than subtle energy differences connected with misalignment.…”

“…The z-coordinates of graphene along the dashed traces above the BN plane are reported below each panel; the amplitude of this out-of-plane corrugation agrees, quantitatively, very well with experimental findings. [9,16] flatness of the adsorbate (i.e.,negligible surface-normal displacements of the monolayer), making the problem strictly two-dimensional. The physics of this misalignment has been clear for a long time.…”