Two-dimensional magnetotransport in a black phosphorus naked quantum well

Abstract

Black phosphorus (bP) is the second known elemental allotrope with a layered crystal structure that can be mechanically exfoliated to atomic layer thickness. Unlike metallic graphite and semi-metallic graphene, bP is a semiconductor in both bulk and few-layer form. Here we fabricate bP-naked quantum wells in a back-gated field effect transistor geometry with bP thicknesses ranging from 6±1 nm to 47±1 nm. Using a polymer encapsulant, we suppress bP oxidation and observe field effect mobilities up to 900 cm2 V−1 s−1 and on/off current ratios exceeding 105. Shubnikov-de Haas oscillations observed in magnetic fields up to 35 T reveal a 2D hole gas with Schrödinger fermion character in a surface accumulation layer. Our work demonstrates that 2D electronic structure and 2D atomic structure are independent. 2D carrier confinement can be achieved without approaching atomic layer thickness, advantageous for materials that become increasingly reactive in the few-layer limit such as bP.

Dephasing in strongly anisotropic black phosphorus

“…Here, we have observed WL in a 65-nm-thick bP FET (which forms a ∼3-nm-thick 2D hole gas in an accumulation layer at the bP/SiO 2 interface [29]) whose dephasing length exponent is found to be suppressed, and closer to a value of 1/3. We attribute this WL behavior to the anisotropic nature of the puckered bP atomic crystal structure whose hole dispersion is distinct along the hard (along) and easy (against) axis of the puckers; see Fig.…”

Emerging Trends in Phosphorene Fabrication towards Next Generation Devices

“…Mechanical exfoliation using scotch‐tape has been reported in many studies 28, 29, 35, 36, 37, 148. The isolation of single‐layer phosphorene that can be performed by means of a classical scotch tape (also called as blue Nitto tape)‐based mechanical exfoliation is divided into two steps: (i) Exfoliation of BP layers from bulk BP using scotch tape and (ii) transfer of the exfoliated BP layers onto the substrate (usually SiO 2 ).…”

“…The monolayer of BP, known as phosphorene, exhibits physical properties that can be significantly different from those of its bulk counterpart 16. Phosphorene has changed the landscape of many research areas in science and technology, particularly in condensed matter physics, and it has received much attention recently for its use as the base component of novel nanodevices, e.g., transistors, nanomechanical resonators, photovoltaics, photodetectors, batteries and sensors 9, 10, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37…”

Magnetoelectronic properties of multilayer black phosphorus

“…Similar hBN encapsulation has also been applied to other 2D materials such as graphene 24 and transition metal dichalcogenides 25 to achieve record mobilities. Indeed, the high quality BP has made possible the first observation of prominent quantum magneto-oscillations in these devices [19][20][21][22][23] and quantum Hall effect ? .…”