Excellent electronic transport in heterostructures of graphene and monoisotopic boron-nitride grown at atmospheric pressure

Abstract

Hexagonal boron nitride (BN), one of the very few layered insulators, plays a crucial role in 2D materials research. In particular, BN grown with a high pressure technique has proven to be an excellent substrate material for graphene and related 2D materials, but at the same time very hard to replace. Here we report on a method of growth at atmospheric pressure as a true alternative for producing BN for high quality graphene/BN heterostructures. The process is not only more scalable, but also allows to grow isotopically purified BN crystals. We employ Raman spectroscopy, cathodoluminescence, and electronic transport measurements to show the high-quality of such monoisotopic BN and its potential for graphene-based heterostructures. The excellent electronic performance of our heterostructures is demonstrated by well developed fractional quantum Hall states, ballistic transport over distances around 10 µm at low temperatures and electron-phonon scattering limited transport at room temperature.

Comparison and Selection of Data Processing Methods for the Application of Cr3+ Photoluminescence Piezospectroscopy to Thermal Barrier Coatings

“…Cr 3+ photoluminescence piezospectroscopy is not the only spectromechanical method. Other techniques, such as cathodoluminescence spectroscopy [30,31], Eu 3+ photoluminescence piezospectroscopy [11,32], and micro-Raman spectroscopy [33][34][35][36][37][38], have been broadly applied to the stress/strain analyses of different materials and structures. Fitting functions, such as Lorentzian, Gaussian, and Psd-Voigt functions, have been used to identify the positions and intensities of the characteristic peaks in the spectra detected from samples with external or internal stress.…”

High-quality electrical transport using scalable CVD graphene

“…Moreover, the device structure employed here is quite simple and does not include single-crystalline graphite gates that would further reduce n * by screening of remote disorder [32]. In Figure 2f we plot µD for D1-3 as a function of n (solid lines, excluding the regions |n| < n * ), together with µD = 4eW/(πh 2 n) 1/2 (dashed lines, where h is the Planck's constant), which is the expected carrier-dependent mobility for ballistic transport over distance W [33], which we set equal to the devices' width (2.5 μm, 2 μm and 3 μm for D1, D2 and D3, respectively). This functional dependence captures very well the behavior of the samples at large n, indicating that the devices' finite dimensions represent the primary limitation to the carriers' motion.…”

“…Engineering clean interfaces over large areas in CVD-G-based hetero-stacks is also of great technological relevance and might benefit from assembly in vacuum conditions [43] and post-assembly thermal and/or nano-mechanical treatment [29]. [33]. The inset shows separate enlarged views of the main panel for hole and electron doping, with Log scale on the x axis, highlighting the peak region of µD.…”

Hexagonal Boron Nitride Crystal Growth from Iron, a Single Component Flux

“…Two-dimensional (2D) materials are receiving immense interest for their properties and their proposed applications in optics, electronics, nanophotonics, optoelectronics, and photovoltaics . Of these, hexagonal boron nitride (hBN) has attracted much attention due to its exciting applications as an excellent substrate for graphene devices, , a protective encapsulant for other 2D materials, , a heat management layer in flexible nanoelectronic devices, , a single-photon emitter, and a platform for nanophotonic devices . In addition, due to its chemical and thermal stability, atomic flatness, large energy band gap (5.9 eV), and absence of dangling bonds and surface charge traps, hBN is an ideal ultrathin insulator and gate dielectric …”