Few-Layer WSe₂ Schottky Junction-Based Photovoltaic Devices through Site-Selective Dual Doping

Abstract

Ultrathin sheets of two-dimensional (2D) materials like transition metal dichalcogenides have attracted strong attention as components of high-performance light-harvesting devices. Here, we report the implementation of Schottky junction-based photovoltaic devices through site-selective surface doping of few-layer WSe in lateral contact configuration. Specifically, whereas the drain region is covered by a strong molecular p-type dopant (NDP-9) to achieve an Ohmic contact, the source region is coated with an AlO layer, which causes local n-type doping and correspondingly an increase of the Schottky barrier at the contact. By scanning photocurrent microscopy using green laser light, it could be confirmed that photocurent generation is restricted to the region around the source contact. The local photoinduced charge separation is associated with a photoresponsivity of up to 20 mA W and an external quantum efficiency of up to 1.3%. The demonstrated device concept should be easily transferrable to other van der Waals 2D materials.

Optoelectronics of Multijunction Heterostructures of Transition Metal Dichalcogenides

“…In order to confirm the locations where the photocurrent is generated, a scanning photocurrent microscopy was adopted − using a 532 nm laser with ∼9 μW power, as shown in Figure and Figures S9–11. Most of the images show the strong photocurrent signal at the junction with forward biases.…”

Modulation of Junction Modes in SnSe2/MoTe2 Broken-Gap van der Waals Heterostructure for Multifunctional Devices

“…The atomically thin and dangling bond-free two-dimensional (2D) layered semiconducting transition-metal dichalcogenides (s-TMDs) have a significant potential for use in post-Si technologies, specifically in optoelectronic and electronic devices. , Although the carrier-type conversion in s-TMDs has been implemented through surface modification via various chemical and physical methods, it is infeasible to delicately control the carrier concentration. − Thus, p–n-junction electronic devices with manually stacked 2D materials have been proposed. These structures allow for the creation of unlimited combinations with various functions and extraordinary characteristics, such as Esaki diodes, tunneling diodes, photovoltaics, − and photodectectors. − Nevertheless, electronic devices having one or more characteristics are difficult to realize because certain devices require different energy-band structures depending on their applications.…”

Significantly Increased Photoresponsivity of WSe2‐Based Transistors through Hybridization with Gold‐Tetraphenylporphyrin as Efficient n‐Type Dopant

“…The inset of Figure b shows a schematic energy band diagram of WSe 2 /Au‐TPP. As the thickness of the WSe 2 flake was thinner than 10 nm, the applied V G could affect the entire WSe 2 flake without screening effect, leading to the increase in photoinduced electron transfer from Au‐TPP to WSe 2 with V G …”