Introduction of Interfacial Charges to Black Phosphorus for a Family of Planar Devices

Abstract

The capabilities to tune the conduction properties of materials by doping or electric fields are essential for the design of electronic devices. However, in two-dimensional materials substitutional doping has been achieved in only a few systems, such as Nb substitutional doping in MoS. Surface charge transfer is still one of the popular ways to control whether the conduction is dominated by holes or electrons. Here, we demonstrate that a capping layer of cross-linked poly(methyl methacrylate) modifies the potential in a black phosphorus (BP) layer so that conduction in the absence of an external electric field is dominated by electrons, rather than holes. Using this technique to form adjoining regions dominated by hole and electron conduction, a family of novel planar devices, such as BP-gated diodes, BP bidirectional rectifier, and BP logic inverters, can be fabricated. The devices are potentially useful for electronic applications, including rectification and switching.

MoTe2 p–n Homojunctions Defined by Ferroelectric Polarization

“…[ 22,23 ] The related methods usually involve vertically stacked heterojunctions and lateral carrier manipulation in homojunctions, such as thickness modulation, [ 24–27 ] elemental doping, [ 28–31 ] and surface modification. [ 32–35 ] In the vertical stacked heterojunctions, the band bending is confirmed in both the lateral and vertical directions via spatial photocurrent mapping and surface potential profiles combined with finite element simulations, [ 36 ] in which the band alignments can be tuned by the back gate voltage. [ 37,38 ] However, the band bending of the in‐plain p–n junction only occurs in the lateral direction.…”

Stabilizing ultra-thin black phosphorus with in-situ-grown 1 nm-Al2O3 barrier

“…4,7,20 Aiming at the same result, thick oxide layers grown on BP have been probed [e.g., 100 nm of SiO 2 grown by inductively coupled plasma chemical vapor deposition 21 or 10 nm of HfO 2 grown by atomic layer deposition (ALD) 19 ] and found to secure the environmental stability of BP at a week scale. Also, numerous attempts have focused on the passivation via a relatively thick (10 nm or above) Al 2 O 3 layer grown on top of the BP flakes by ALD.…”

“…32 Thin capping may simultaneously passivate and serve as a tunnel barrier (which may even lead to improved electrical contacts 33,34 ) representing a double advantage over thick capping in which electrical contacts must be patterned before passivation (ex-situ). 20 Finally, this leads us to an important limitation in many of the reported procedures, which lies in their ex-situ character: the time exposure to air, even if very short, of the samples during the fabrication process 23 is critical for the degradation of the thinnest few-layered BP flakes. This is unfortunate considering that the modulation amplitude of the bandgap energy is maximum in the range of 1 to 5 layers.…”

In‐Plane Black Phosphorus/Dicobalt Phosphide Heterostructure for Efficient Electrocatalysis

“…[8] Because the in-plane charge carrier mobility of 2D materials is much higher than that between interlayers,inplane heterostructures have intrinsic advantages. [9] Some interesting BP heterostructures have been fabricated by techniques such as ion implantation, [10] electron doping, [11] surface coating, [12] in situ reduction [13] and van der Waals chemistry. [14] In these heterostructures,BPisgenerally used to promote charge separation at the semiconductor heterojunction or improve the conductivity.…”