Two-dimensional (2D) layered materials-based p-n diode is an essential element in the modern semiconductor industry for facilitating the miniaturization and structural flexibility of devices with high efficiency for future optoelectronic...

The construction of high-speed electronic devices that can be integrated using a single two-dimensional (2D) semiconductor with high performance remains challenging due to the absence of locally selective doping methods. In this study, we have demonstrated that the selective opposite polarities (p-type or n-type) from an intrinsic 2H-MoTe2 field-effect transistor (FET) can be configured through carrier type band modulation in molybdenum ditelluride (MoTe2) caused by the charge storage interface in MoTe2/BN vdW heterostructures upon UV illumination with electrostatic gate bias. With this approach, we demonstrate a lateral p-i-n homojunction diode (p-MoTe2/intrinsic-MoTe2/n-MoTe2) using a single two-dimensional semiconductor (2H-MoTe2) where an intrinsic FET (i-type region) is sandwiched between p- and n-type FETs. Electrical performance of such a p-i-n diode demonstrates an ideal rectifying behavior with a rectification ratio (I f/I r) of up to ∼1.4 × 106 at zero gate bias with an ideal value of the ideality factor of nearly ∼1. To support optoelectrical doping, Kelvin probe force microscopy (KPFM) measurements are performed where p- and n-type MoTe2 channels show work function values of ∼5.0 and ∼ 4.55 eV, respectively, with a built-in potential of ∼450 mV. In the photovoltaic mode, the p-i-n diode shows excellent photodetection properties under an illumination of 600 nm, a maximum value of responsivity of 1.10 A/W, and a specific detectivity value of 3.0 × 1012 Jones. The device shows ultrafast photoresponses, where the response speed (τr/τf) is estimated to be 10/20 ns. The proposed research offers an opportunity for creating stable p-i-n homojunction diodes for high-speed electronics with low power consumption using 2D materials.

p–n Diodes showed a sound self-biased photovoltaic behavior upon light illumination and also achieved VOC switching behavior at the p–n diode state by switching on and off the light.

Noble metal dichalcogenides (NMDs) are two-dimensional (2D) layered materials that exhibit outstanding thickness-dependent tunable-bandgaps that can be suitable for various optoelectronic applications.

Here, van der Waals multi‐heterojunctions (PN, NP, PIN, and NPN) are fabricated by stacking of MoTe2, hexagonal boron nitride (h‐BN), and MoSe2 nanoflakes using a mechanical‐exfoliation technique where the dynamic rectification is examined. Low‐resistance metal contacts Al/Au and Pt/Au are applied to MoSe2 and MoTe2, respectively, and gate‐dependent rectifying behavior is achieved, with a rectification ratio of up to 105 in PN devices. It is found that the performance of the device is enhanced by placing an interfacial layer h‐BN between two opposite layers of 2D materials where the rectification ratio is found to be >106 with the ideality factor ≈1.3 in the PIN devices. Also, using the conventional Richardson's plot, the barrier heights of PN and PIN diodes are calculated to be 260 and 490 meV at zero gate bias, respectively. As well, the devices exhibit good performance with a built‐in electric field observed in both PN and PIN diodes, which gives rise to an open‐circuit voltage (Voc) and short‐circuit current (Isc) under zero external bias. Remarkably, it is found that the performance of the devices also gets better by forming double heterojunction (NPN) layer than PN or NP layers. The device is also tested for a rectification application, and it successfully rectifies an input alternating‐current signal. These findings are important for the development of nano‐ and optoelectronics devices.

Here, novel lateral PtSe2 p-n junctions are fabricated based on the PtSe2/BN/graphene (Gr) van der Waals heterostructures upon illumination of visible light by optical excitation of mid-gap point defects in...

Two-dimensional (2D) materials can be implemented in several functional devices for future optoelectronics and electronics applications. Remarkably, recent research on p–n diodes by stacking 2D materials in heterostructures or homostructures (out of plane) has been carried out extensively with novel designs that are impossible with conventional bulk semiconductor materials. However, the insight of a lateral p–n diode through a single nanoflake based on 2D material needs attention to facilitate the miniaturization of device architectures with efficient performance. Here, we have established a physical carrier-type inversion technique to invert the polarity of MoTe2-based field-effect transistors (FETs) with deep ultraviolet (DUV) doping in (oxygen) O2 and (nitrogen) N2 gas environments. A p-type MoTe2 nanoflake transformed its polarity to n-type when irradiated under DUV illumination in an N2 gaseous atmosphere, and it returned to its original state once irradiated in an O2 gaseous environment. Further, Kelvin probe force microscopy (KPFM) measurements were employed to support our findings, where the value of the work function changed from ∼4.8 and ∼4.5 eV when p-type MoTe2 inverted to the n-type, respectively. Also, using this approach, an in-plane homogeneous p–n junction was formed and achieved a diode rectifying ratio (If/Ir) up to ∼3.8 × 104. This effective approach for carrier-type inversion may play an important role in the advancement of functional devices.

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