Key Takeaways & Executive Findings
- •• The mixed-dimensional type II heterojunction of GaSb nanowires (NWs) and Bi2O2Se nanosheets (NSs) with a built-in electric field of ~140 meV is successfully constructed. • As-fabricated NW/NS and NW array/NS mixed-dimensional heterojunction photodetectors exhibit as-expected high-performance self-powered photodetection behaviors, including ultralow Idark (0.07 and 0.08 pA), superior Ilight/Idark ratios (82 and 182) and ultrafast photoresponse (<2/2 and 6/4 ms). • As-fabricated NW array/NS mixed-dimensional heterojunction self-powered photodetector promises the future imaging and photocommunication. • The self-powered photodetector performance can be further enhanced by fabricating the NW array/NS mixed-dimensional heterojunction using a contact printing technique.
Abstract
With high surface-to-volume ratio, the abundant surface states and high carrier concentration are challenging the near-infrared photodetection behaviors of narrow band gap semiconductors nanowires. In this study, the narrow band gap semiconductor of Bi2O2Se nanosheets (NSs) is adopted to construct mixed-dimensional heterojunctions with GaSb nanowires (NWs) for demonstrating the impressive self-powered NIR photodetection. Benefiting from the built-in electric field of ~140 meV, the as-constructed NW/NS mixed-dimensional heterojunction self-powered photodetector shows the low dark current of 0.07 pA, high Ilight/Idark ratio of 82 and fast response times of <2/2 ms at room temperature. The self-powered photodetector performance can be further enhanced by fabricating the NW array/NS mixed-dimensional heterojunction by using a contact printing technique. The excellent photodetection performance promises the as-constructed NW/NS mixed-dimensional heterojunction self-powered photodetector in imaging and photocommunication.
1. Introduction
Near-infrared (NIR) photodetector has attracted much more attention in remote sensing, medical imaging and environmental monitoring, due to its ability to penetrate biological tissues and the atmosphere [1–12]. With the moderate narrow band gap of 0.72 eV, the highest hole mobility of 850 cm2 V−1 s−1 among III–V semiconductors and the broad spectral absorption ability, GaSb nanowires (NWs) have been utilized for near-infrared photodetection in the past decade, which is in forms of photoconductor, field-effect phototransistor and Schottky photodiode [13–17]. With high surface-to-volume ratio, the abundant surface states and high carrier concentration are challenging the NIR photodetection behaviors of GaSb NWs [17–19]. First of all, the surface state will act as the carrier traps, resulting in the bias stress instability of GaSb NW NIR photodetectors [15]. Furthermore, the surface state will cause the famous Fermi level pinning, resulting in the inability to modulate the dark current (Idark) of the NIR photodetector through the metal/semiconductor contact barrier [13, 20]. At the same time, the high carrier concentration will cause the NIR photodetector to suffer from a large Idark, resulting in a low Ilight/Idark [21].
To date, the surface passivation, van der Waals integration and construction of heterojunction have been developed to optimize the NIR photodetection behaviors of low-dimensional semiconductors [13, 20, 22–24]. Among them, the construction of heterojunction is a popular and meaningful approach, because the built-in electric field and depletion region would be introduced at the semiconductor–semiconductor heterointerfaces by designing reasonably the energy band engineering, benefiting to the quick separation and collection of photogenerated electron–hole pairs, which facilitates the faster photoresponse speed [25–31]. Furthermore, the built-in electric field and depletion region benefit to the success construction of self-powered photodetector, which operates effectively without an external energy source, hold great potential applications in Internet of Things and low power dissipation. At the same time, the Idark will be significantly suppressed and photosensitivity is effectively enhanced due to the barrier at the interfaces and the absence of an external bias, benefiting to the smart photodetection of NIR light [32].
It is worth pointing out that the type II semiconductor heterostructure promotes the separation of photogenerated carriers by directing electrons and holes across the interface in opposite directions [33–35]. This property makes the type II heterojunctions ideal candidates for ultrasensitive and self-powered photodetectors [36–41]. With narrow band gap of 0.8 eV, Bi2O2Se nanosheets (NSs) are adopted to construct mixed-dimensional type II heterojunctions with GaSb NWs for demonstrating the impressive self-powered NIR photodetection, optical imaging and photocommunication in this work [42, 43]. Benefiting from the built-in electric field, the as-fabricated NW/NS heterojunction photodetector exhibits excellent self-powered photodetection performance, that is, the Idark is as low as 0.07 pA, the Ilight/Idark ratio is as high as 82, and the response times are less than 2/2 ms at room temperature.
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Guangcan Wang, Zixu Sa, Zeqi Zang, Pengsheng Li, Mingxu Wang, Bowen Yang, Xiaoyue Wang, Yanxue Yin, Zai-xing Yang (2025). Mixed-Dimensional Nanowires/Nanosheet Heterojunction of GaSb/Bi2O2Se for Self-Powered Near-Infrared Photodetection and Photocommunication. Nano-Micro Letters. https://doi.org/10.1007/s40820-025-01793-2
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Frequently Asked Questions
What is the main achievement of this research?
The research successfully constructs a mixed-dimensional type II heterojunction of GaSb nanowires and Bi2O2Se nanosheets, achieving a self-powered near-infrared photodetector with ultralow dark current (0.07 pA), high Ilight/Idark ratio (82), and ultrafast response (<2/2 ms).
How does the built-in electric field contribute to the photodetector performance?
The built-in electric field of ~140 meV facilitates the separation and collection of photogenerated electron-hole pairs, enabling self-powered operation and suppressing dark current, leading to high sensitivity and fast response.
What are the potential applications of this photodetector?
The photodetector shows promise for optical imaging and photocommunication, as well as applications in remote sensing, medical imaging, and environmental monitoring.
How was the performance further enhanced?
By fabricating a NW array/NS heterojunction using a contact printing technique, the photodetector performance was further enhanced, achieving even lower dark current (0.08 pA) and higher Ilight/Idark ratio (182).
What is the significance of using Bi2O2Se nanosheets?
Bi2O2Se nanosheets have a narrow band gap of 0.8 eV, which complements GaSb nanowires to form a type II heterojunction, enabling efficient charge separation and self-powered NIR photodetection.
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