Interface confinement on the exciton recombination in thin CdS/ZnO shell/core nanowires
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Interface confinement on the exciton recombination in thin CdS/ZnO shell/core nanowires Yan He1,2 · Sumei Hu1 · Weiling Zhu1 · Gang Ouyang2 Received: 18 February 2020 / Accepted: 27 May 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The modulation of exciton recombination is one of the core issues for the electronic/optoelectronic devices. Here, we investigate the exciton recombination and surface depletion of ZnO nanowires under various interface conditions in terms of continuum medium mechanics and bond relaxation method. We find that the enhancement of donor concentration, nanowire dimension and external temperature can modify the carrier recombination, surface barrier height and surface depletion depth. Moreover, coated a thin epitaxial layer on the nanowires is of great benefit to reduce the surface state for suppression of recombination rate. The related mechanism on the interface confinement has also been clarified. Our predictions agree well with the experimental measurements, which provide an effective guidance for the organization of electronic device design. Keywords Exciton recombination · Thin CdS/ZnO shell/core nanowires · Interface confinement · Surface depletion
1 Introduction Recently, ZnO nanowires (NWs) have gained much attention for a range of nanoscale electronic and photonic devices due to their fascinating optoelectronic, biosensors and piezoelectric as well as the biocompatible and environmental friendly properties [1–3]. In particular, as the surface-to-volume ratio (SVR) becomes increase with shrinking diameter of NWs, the influence of surface states on carrier transport properties would be arisen, resulting in the modification of recombination process and the increment of carriers loss at the surface layer [4, 5]. Therefore, understanding the behavior of surface carriers and the size effect of surface recombination as well as the surface depletion layer becomes a significant
* Yan He [email protected] * Gang Ouyang [email protected] 1
College of Science, Guangdong University of Petrochemical Technology, Maoming 525000, Guangdong, China
Key Laboratory of Low‑Dimensional Quantum Structures and Quantum Control of Ministry of Education, Key Laboratory for Matter Microstructure and Function of Hunan Province, Synergetic Innovation Center for Quantum Effects and Applications (SICQEA), Hunan Normal University, Changsha 410081, China
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challenging for the enhancing of electronic performance in NW-based devices [6, 7]. Generally, shrinking the dimension of NWs to nanoscale, the surface effect induced by the dangling bonds and impurities would force the surface bands to be bent and play a significant influence on the behavior of carriers, thereby resulting in the production of surface depletion layer [8]. To date, a lot of efforts have been carried out to explore the influence of surface depletion layer on the carriers transport properties and recombination process both theoretically [9–15] and experimentally [16–23]. In fact, in order to depress the in
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