Light‐Induced Bipolar Photoresponse with Amplified Photocurrents in an Electrolyte‐Assisted Bipolar p–n Junction

Abstract

The p–n junction with bipolar characteristics sets the fundamental unit to build electronics while its unique rectification behavior constrains the degree of carrier tunability for expanded functionalities. Herein, a bipolar‐junction photoelectrode employed with a gallium nitride (GaN) p–n homojunction nanowire array that operates in electrolyte is reported, demonstrating bipolar photoresponse controlled by different wavelengths of light. Significantly, with rational decoration of a ruthenium oxides (RuOx) layer on nanowires guided by theoretical modeling, the resulting RuOx/p–n GaN photoelectrode exhibits unambiguously boosted bipolar photoresponse by an enhancement of 775% and 3000% for positive and negative photocurrents, respectively, compared to the pristine nanowires. The loading of the RuOx layer on nanowire surface optimizes surface band bending, which facilitates charge transfer across the GaN/electrolyte interface, meanwhile promoting the efficiency of redox reaction for both hydrogen evolution reaction and oxygen evolution reaction which corresponds to the negative and positive photocurrents, respectively. Finally, a dual‐channel optical communication system incorporated with such photoelectrode is constructed with using only one photoelectrode to decode dual‐band signals with encrypted property. The proposed bipolar device architecture presents a viable route to manipulate the carrier dynamics for the development of a plethora of multifunctional optoelectronic devices for future sensing, communication, and imaging systems.

High-Performance Photodetector Based on the ReSe2/PtSe2 van der Waals Heterojunction

“…Due to the limitations of these single materials, it is generally hard to meet the increasingly complex application needs in reality. Since the discovery of graphene, more and more high-performance photodetectors made of two-dimensional (2D) layered materials, with high responsivity and high detectivity have been reported. − For practical applications, a good photodetector should have high a signal-to-noise ratio, a short response time, high responsivity, and low or no power dissipation . Van der Waals heterostructures (vdWHs) made of 2D materials provide an innovative approach to solving the above problems .…”

Fully Epitaxial Semiconductor Photoelectrode for UV–VIS Dual-Band Photodetection

“…16−23 In addition, it is also noted that the existing dual-band III-nitride nanowire-based PEC-PDs require additional photocatalysts or other material coatings to have dual-band photodetection capability. 1,2,14,15 In this study, we demonstrate fully epitaxial n-GaN/p-InGaN nanowire photoelectrodes, which extend the dual-band photodetection of III-nitride nanowire-based PEC-PDs to the visible range. Photodetection at both 405 and 302 nm is achieved, together with a dual-polarity photocurrent under the 302 nm light illumination by tuning the applied potential.…”

“…However, the spectrally distinctive photoelectrodes demonstrated by now are mostly by chemical methods and may not be compatible with existing epitaxial semiconductor device platforms; more critically, chemical stability is an issue. ,,− On the other hand, with the recent remarkable progress on high-performance dual-band PEC-PDs with epitaxial, and highly chemically stable and mechanically strong III-nitride nanowires, the dual-band photodetection has been limited to the UV range, ,,,, whereas in principle, their ultrawide and tunable bandgap, as well as the unique band alignment with respect to water redox potentials, is able to support a much broader spectrally distinctive dual-band photodetection. Extending such PEC-PDs to the visible spectral range is also highly desirable, especially in the blue range, in the sense that blue light is the emerging light wavelength for on-chip optical communications and underwater communications. − In addition, it is also noted that the existing dual-band III-nitride nanowire-based PEC-PDs require additional photocatalysts or other material coatings to have dual-band photodetection capability. ,,, In this study, we demonstrate fully epitaxial n-GaN/p-InGaN nanowire photoelectrodes, which extend the dual-band photodetection of III-nitride nanowire-based PEC-PDs to the visible range. Photodetection at both 405 and 302 nm is achieved, together with a dual-polarity photocurrent under the 302 nm light illumination by tuning the applied potential.…”

“…However, the spectrally distinctive photoelectrodes demonstrated by now are mostly by chemical methods and may not be compatible with existing epitaxial semiconductor device platforms; more critically, chemical stability is an issue. 3,4,6−13 On the other hand, with the recent remarkable progress on high-performance dual-band PEC-PDs with epitaxial, and highly chemically stable and mechanically strong III-nitride nanowires, the dual-band photodetection has been limited to the UV range, 1,2,5,14,15 whereas in principle, their ultrawide and tunable bandgap, as well as the unique band alignment with respect to water redox potentials, is able to support a much broader spectrally distinctive dual-band photodetection. Extending such PEC-PDs to the visible spectral range is also highly desirable, especially in the blue range, in the sense that blue light is the emerging light wavelength for on-chip optical communications and underwater communications.…”

Plasma-Engineered Amorphous Metal Oxide Nanostructure-Based Low-Power Highly Responsive Phototransistor Array for Next-Generation Optoelectronics

“…In the era of artificial intelligence, the development of cost-effective, energy-efficient, and high-performance broadband photodetectors holds great potential for next-generation electronic applications. − Photodetectors, in particular, play an indispensable role in artificial human vision systems, LiDAR, face recognition, security surveillance, optical communication, biomedical imaging, etc. Commercially available detectors commonly employ materials such as GaN, ZnO, Si, and InGaAs to detect ultraviolet (UV) to near-infrared (NIR) lights. − Detecting different wavelengths requires specific semiconductors for photodetectors.…”