Abstract
Owing to their practical applications, two‐dimensional semiconductor p–n diodes have attracted enormous attention. Over the past decade, various methods, such as chemical doping, ...heterojunction structures, and metallization using metals with different work functions, have been reported for fabrication of such devices. In this study, a lateral p–n junction diode is formed in tungsten diselenide (WSe
2
) using a combination of edge and surface contacts. The appearance of amorphous tungsten oxide at etched WSe
2
, and the formation of a junction near the edge contact, are verified by high‐resolution transmission electron microscopy. The device demonstrates high on/off ratio for both the edge and surface contacts, with respective values of 10
7
and 10
8
. The diode can achieve extremely high mobility of up to 168 cm
2
V
−1
s
−1
and a rectification ratio of 10
3
. The ideality factor is 1.11 at a back gate voltage
V
G
= 60 V at 300 K. The devices with encapsulation of hexagonal boron nitride exhibit good stability to atmospheric exposure, over a measured period of 2 months. In addition, the architecture of the contacts, which is based on a single‐channel device, should be advantageous for the implementation of more complicated applications such as inverters, photodetectors, and light‐emitting diodes.
Transition metal dichalcogenides (TMDs) are of great interest owing to their unique properties. However, TMD materials face two major challenges that limit their practical applications: contact ...resistance and surface contamination. Herein, a strategy to overcome these problems by inserting a monolayer of hexagonal boron nitride (h-BN) at the chromium (Cr) and tungsten disulfide (WS
) interface is introduced. Electrical behaviors of direct metal-semiconductor (MS) and metal-insulator-semiconductor (MIS) contacts with mono- and bilayer h-BN in a four-layer WS
field-effect transistor (FET) are evaluated under vacuum from 77 to 300 K. The performance of the MIS contacts differs based on the metal work function when using Cr and indium (In). The contact resistance is significantly reduced by approximately ten times with MIS contacts compared with that for MS contacts. An electron mobility up to ≈115 cm
V
s
at 300 K is achieved with the insertion of monolayer h-BN, which is approximately ten times higher than that with MS contacts. The mobility and contact resistance enhancement are attributed to Schottky barrier reduction when h-BN is introduced between Cr and WS
. The dependence of the tunneling mechanisms on the h-BN thickness is investigated by extracting the tunneling barrier parameters.
Two-dimensional transition metal dichalcogenides (TMDs) are promising materials for semiconductor nanodevices owing to their flexibility, transparency, and appropriate band gaps. A variety of ...optoelectronic and electronic devices based on TMDs p-n diodes have been extensively investigated due to their unique advantages. However, improving their performance is challenging for commercial applications. In this study, we propose a facile and doping-free approach based on the contact engineering of a few-layer tungsten di-selenide to form a lateral p-n homojunction photovoltaic. By combining surface and edge contacts for p-n diode fabrication, the photovoltaic effect is achieved with a high fill factor of ≈0.64, a power conversion efficiency of up to ≈4.5%, and the highest external quantum efficiency with a value of ≈67.6%. The photoresponsivity reaches 283 mA/W, indicating excellent photodiode performance. These results demonstrate that our technique has great potential for application in next-generation optoelectronic devices.
A direct insulator-quantum Hall (I-QH) transition corresponds to a crossover/transition from the insulating regime to a high Landau level filling factor ν > 2 QH state. Such a transition has been ...attracting a great deal of both experimental and theoretical interests. In this study, we present three different two-dimensional electron systems (2DESs) which are in the vicinity of nanoscaled scatterers. All these three devices exhibit a direct I-QH transition, and the transport properties under different nanaoscaled scatterers are discussed.
Two-dimensional transition metal dichalcogenides (TMDs) are promising materials for semiconductor nanodevices owing to their flexibility, transparency, and appropriate band gaps. A variety of ...optoelectronic and electronic devices based on TMDs
diodes have been extensively investigated due to their unique advantages. However, improving their performance is challenging for commercial applications. In this study, we propose a facile and doping-free approach based on the contact engineering of a few-layer tungsten di-selenide to form a lateral
homojunction photovoltaic. By combining surface and edge contacts for
diode fabrication, the photovoltaic effect is achieved with a high fill factor of ≈0.64, a power conversion efficiency of up to ≈4.5%, and the highest external quantum efficiency with a value of ≈67.6%. The photoresponsivity reaches 283 mA/W, indicating excellent photodiode performance. These results demonstrate that our technique has great potential for application in next-generation optoelectronic devices.
Owing to their practical applications, two‐dimensional semiconductor p–n diodes have attracted enormous attention. Over the past decade, various methods, such as chemical doping, heterojunction ...structures, and metallization using metals with different work functions, have been reported for fabrication of such devices. In this study, a lateral p–n junction diode is formed in tungsten diselenide (WSe2) using a combination of edge and surface contacts. The appearance of amorphous tungsten oxide at etched WSe2, and the formation of a junction near the edge contact, are verified by high‐resolution transmission electron microscopy. The device demonstrates high on/off ratio for both the edge and surface contacts, with respective values of 107 and 108. The diode can achieve extremely high mobility of up to 168 cm2 V−1 s−1 and a rectification ratio of 103. The ideality factor is 1.11 at a back gate voltage VG = 60 V at 300 K. The devices with encapsulation of hexagonal boron nitride exhibit good stability to atmospheric exposure, over a measured period of 2 months. In addition, the architecture of the contacts, which is based on a single‐channel device, should be advantageous for the implementation of more complicated applications such as inverters, photodetectors, and light‐emitting diodes.
In this study, a lateral p–n junction diode is formed in WSe2 using a combination of edge and surface contacts with extremely high performance. A rectification ratio of 103 and the ideality factor of 1.11 are achieved by the WSe2 single‐channel device. This should be advantageous for the implementation of more complicated applications such as inverters, photodetectors, and light‐emitting diodes.
The first demonstration of a mid-infrared optical parametric oscillator pumped by 1-μm optical vortex pulses is presented. A 0.5-mJ 2-μm fractional vortex pulse having half-integer topological charge ...is generated. Using this system, 0.24-mJ vortex pulses with a topological charge of 1 can be created. The topological charges of the mid-infrared vortex pulses are observed by an interferometric technique in combination with second-harmonic frequency conversion.
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