Independent Band Modulation in 2D van der Waals Heterostructures via a Novel Device Architecture

Abstract

Benefiting from the technique of vertically stacking 2D layered materials (2DLMs), an advanced novel device architecture based on a top‐gated MoS2/WSe2 van der Waals (vdWs) heterostructure is designed. By adopting a self‐aligned metal screening layer (Pd) to the WSe2 channel, a fixed p‐doped state of the WSe2 as well as an independent doping control of the MoS2 channel can be achieved, thus guaranteeing an effective energy‐band offset modulation and large through current. In such a device, under specific top‐gate voltages, a sharp PN junction forms at the edge of the Pd layer and can be effectively manipulated. By varying top‐gate voltages, the device can be operated under both quasi‐Esaki diode and unipolar‐Zener diode modes with tunable current modulations. A maximum gate‐coupling efficiency as high as ≈90% and a subthreshold swing smaller than 60 mV dec−1 can be achieved under the band‐to‐band tunneling regime. The superiority of the proposed device architecture is also confirmed by comparison with a traditional heterostructure device. This work demonstrates the feasibility of a new device structure based on vdWs heterostructures and its potential in future low‐power electronic and optoelectronic device applications.

WSe2/SnSe2 vdW heterojunction Tunnel FET with subthermionic characteristic and MOSFET co-integrated on same WSe2 flake

“…Several materials have been investigated by either atomistic simulations or experimental studies. The onset of BTBT has been reported in WSe 2 /MoS 2 , BP/SnSe 2 , BP/MoS 2 , Ge/ MoS 2 and WSe 2 /SnSe 2 heterojunctions 13,[15][16][17][18][19][20][21] . This latter material system has attracted particular interest because of the predicted broken or nearly broken gap band alignment and the peculiar electronic properties of these two members of the transition metal dichalcogenide (TMDC) family.…”

“…In this contest, two-dimensional (2D) materials are promising candidates for the realization of high performance TFETs, providing both a huge variety of electronic properties and the possibility of assembling atomically sharp van der Waals heterojunctions 12 . Several demonstrations of BTBT in 2D-based heterojunctions have been recently reported, with negative differential resistance (NDR) observed in the output characteristic at room or cryogenic temperatures [13][14][15][16][17][18] . However, few 2D TFETs were able to break the 60 mV per decade limit at room temperature 19,20 .…”

Flexible Pyrene/Phenanthro[9,10‐d]imidazole‐Based Memristive Devices for Mimicking Synaptic Plasticity

“…By far, memristor, ferroelectric memory, phase‐change memory, resistive memory device, field‐effect transistor, as well as the silicon‐based complementary metal–oxide–semiconductor (CMOS) circuit have been vigorously studied for realization of an ideal synaptic unit. However, device‐level obstacles and barriers still exist.…”

Intrinsic Electronic Transport Properties and Carrier Densities in PtS2 and SnSe2: Exploration of n+‐Source for 2D Tunnel FETs

“…[4][5][6][7] Here, 2D materials provide an ideal platform for TFETs because the dangling-bond-free van der Waals (vdW) heterointerface minimizes carrier generation and the short tunnel distance at the vdW interface increases the on current. [8,9] To date, n-type 2D-TFETs have been mainly investigated because degenerately doped p + -2D materials, such as Nb-doped p + -MoS 2 , [10,11] intrinsic p + -black phosphorus (BP), [12][13][14][15] and externally doped p + -WSe 2 , [16,17] are available as source materials. Degenerately doped source materials are indispensable for TFETs because their high carrier densities afford sharp SS values as well as high on current by modulating the band alignment only in the channel region, not in the source region.…”