Quantum Hall Effect in Electron-Doped Black Phosphorus Field-Effect Transistors

Abstract

The advent of black phosphorus field-effect transistors (FETs) has brought new possibilities in the study of two-dimensional (2D) electron systems. In a black phosphorus FET, the gate induces highly anisotropic 2D electron and hole gases. Although the 2D hole gas in black phosphorus has reached high carrier mobilities that led to the observation of the integer quantum Hall effect, the improvement in the sample quality of the 2D electron gas (2DEG) has however been only moderate; quantum Hall effect remained elusive. Here, we obtain high quality black phosphorus 2DEG by defining the 2DEG region with a prepatterned graphite local gate. The graphite local gate screens the impurity potential in the 2DEG. More importantly, it electrostatically defines the edge of the 2DEG, which facilitates the formation of well-defined edge channels in the quantum Hall regime. The improvements enable us to observe precisely quantized Hall plateaus in electron-doped black phosphorus FET. Magneto-transport measurements under high magnetic fields further revealed a large effective mass and an enhanced Landé g-factor, which points to strong electron-electron interaction in black phosphorus 2DEG. Such strong interaction may lead to exotic many-body quantum states in the fractional quantum Hall regime.

Strong-field nonlinear optical properties of monolayer black phosphorus

“…Measurements of electric and optical properties of BP imply that it is a promising candidate for novel optoelectronic and photonic applications in the midinfrared to visible frequency range. 2,[19][20][21][22][23][24][25] Devices based on the linear optical response of BP, such as photodetectors [26][27][28][29] and optical modulators, 30 have been reported. Besides, the nonlinear optical properties of BP in the perturbative regime have also been studied, demonstrating its great potential in light absorption, 31 optical modulation, 32 and all-optical signal processing, 33 etc.…”

Magneto‐optic effect of two‐dimensional materials and related applications

“…[ 64 ] All these tunable optical properties and sensitive response with the magnetic field serve as building blocks for the future design of BP based magneto‐optical devices. [ 65 ] Specially, both of BP and TMDCs have many‐body complexes, which usually correlate with exciton effect. [ 66 ] Consequently, Zeeman effect can be used to characterize the many‐body complexes accordingly.…”

Two-Dimensional Pnictogen for Field-Effect Transistors

“…Unlike graphene that can form ohmic contact with metals, 2D pnictogen usually suffers from high contact resistance due to the Schottky barrier at the metal-semiconductor interface, which significantly limits the generation of carrier injection [171–174]. Considering the physical property of Schottky barrier, selecting appropriate metal electrodes for targeted channel materials is fundamentally significant [175–177]. Combining with first-principle calculation and quantum transport simulation, Lu et al systematically investigated 2D pnictogen FETs in contact with a series of metals with a wide work function range in theory [178–183], including Al, Cu, Ni [184], Sc [185], Ti [186], Py [187], Cr [188], Pd, Er [189], Au, and Ag [190] (Figure 8(a)).…”