A strategy to manipulate photocurrent direction in p-n heterojunction nanowires

Semiconductor p-n junctions are boundaries betwixt 2 types of semiconductors (i.e., p-type and n-type semiconductor materials). These junctions are important components of galore modern physics devices.

So far, emblematic p-n junction-based devices person lone allowed existent to travel successful 1 direction, a carnal diagnostic that is associated with each semiconductors. However, this importantly limits their imaginable for processing immoderate types of devices, specified arsenic multi-color detection, precocious imaging and optical connection tools.

Researchers astatine the University of Science and Technology of China person precocious demonstrated that the absorption successful which photocurrent flows wrong p-n heterojunction devices tin beryllium controlled utilizing antithetic wavelengths of light. Their paper, published successful Nature Electronics, could yet pave the mode toward the improvement of caller optoelectronic and physics devices.

"Inspired by the erstwhile find of caller structures oregon instrumentality designs, for example, the adoption of multi-junction oregon tandem architecture, to grow the functionalities beyond a azygous p-n junction, we were aiming to renovate the p-n junctions for caller functionalities," Haiding Sun, 1 of the researchers who carried retired the study, told TechXplore. "A operation of the photoelectric effect and p-n junction semiconductors has often been utilized to physique classical solid-state photodetectors. However, these systems' detection capableness is fundamentally constrained to a definite spectrum range, since they ever make photocurrent flows successful the aforesaid absorption (i.e., a unipolar photoresponse)."

The last nonsubjective of the caller insubstantial by Sun and his colleagues was to make caller p-n heterojunction devices successful which the absorption of photocurrent tin beryllium switched utilizing antithetic wavelengths of light, arsenic this would let them to make caller and much precocious photodetectors. In much circumstantial terms, the squad wanted execute a alleged 'dual-polarity photoresponse' successful p-n heterojunctions to alteration multi-band oregon spectrally distinctive photodetection.

"The quality oculus acts arsenic a earthy photosensor oregon photodetector with precocious sensitivity to antithetic airy (or color)," Sun explained. "However, for man-made, single-semiconductor-material-based detectors, it is hard to separate adjacent betwixt 2 antithetic wavelengths. In different words, it is challenging to physique a photodetector that possesses some spectrally distinctive and broadband responsive features; distinguishing spectral bands without sacrificing the sensitivity/selectivity is peculiarly challenging successful the ultraviolet band, wherever astir materials amusement beardown ultraviolet absorption."

When they are exposed to airy with a wavelength that is adjacent oregon shorter than the optical bandgaps of the materials they are made of, photodetectors based connected accepted p-n junctions typically lone grounds a alleged unipolar photocurrent response; this lone allows electrical currents induced by airy to travel successful 1 direction. To flooded this limitation, Sun and his colleagues devised a caller strategy that enables a dual-polarity photocurrent response, allowing engineers to power the absorption of photocurrent successful n-p junctions.

They utilized this strategy to make a light-detection electrochemical compartment based connected p-AlGaN/n-GaN nanowire heterojunctions placed connected a conductive silicon substrate. This instrumentality exhibited a distinctive photoresponse, with a reversed polarity nether antithetic illumination wavelengths.

"Our recently constructed light-detection electrochemical compartment operates nether a operation of carnal processes (photoelectric conversion and bearer transport successful azygous p-n junction) and chemic process (redox reaction connected nanowire surface), enabling a accelerated and casual mode to separate antithetic spectral bands by simply verifying the polarity of photocurrent," Sun said. "It frankincense offers a caller grade of state to manipulate the bearer transport and frankincense existent travel successful semiconductor devices."

Sun and his colleagues were capable to observe bidirectional photocurrent behaviour successful their instrumentality aft it was exposed to airy with 2 wavelengths (i.e., 254 nm and 365 nm). The 2 wavelengths triggered other redox reactions, the hydrogen improvement absorption (HER) and oxygen improvement absorption (OER) connected the nanowire/electrolyte interface, inducing a reversal successful the polarity of the photocurrent.

The findings could person important implications for the improvement of caller optoelectronic technologies. In fact, Sun and his colleagues showed that bidirectional existent tin beryllium enabled successful p-n heterojunctions, which means that these interfaces could beryllium utilized to make switchable airy imaging, optical connection and filter-less colour favoritism tools. In addition, the instrumentality they created tin run successful h2o oregon successful aqueous environments without requiring blase packaging oregon integrations, and could frankincense beryllium perfect for the instauration of systems that enactment underwater oregon wrong biologic systems.

"Our architecture expands the functionalities of classical semiconductor device operation for multifunctional applications," Sun added. "The adjacent measurement for our probe would beryllium the implementation of the light-detection electrochemical compartment successful the bio-related situation for bio-sensor oregon aesculapian applications."

---

---

© 2021 Science X Network