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Abstract CdS nanowires and film Schottky diodes are fabricated and diode properties are compared. Effect of SnO 2 on CdS film diode properties is investigated. CdS film/Au on 100 nm SnO 2 substrate demonstrates like-resistor characteristics and increase in SnO 2 thickness corrects resistor behavior, however the effective reverse saturation current density J o is significantly high and shunt resistance are considerably low, implying that SnO 2 slightly prevents impurities migration from CdS films into ITO but cause additional issues. Thickness of CdS film on diode properties is further investigated and increasing CdS film thickness improved J o by one order of magnitude, however shunt resistance is obviously low, suggesting intrinsic issues in CdS film. 100 nm CdS nanowire/Au diodes reduce J o by three orders of magnitude in the dark and two orders of magnitude in the light respectively and their shunt resistance is significantly enhanced by 70 times when comparing with those of the CdS film diodes. The wide difference can be attributed to the fact that CdS nanowires overcome intrinsic issues in CdS film and thus demonstrate significantly well- defined diode behavior. Simulation found that CdS nanowire diodes have low compensating acceptor type traps and interface state density of 5.0 × 10 9 cm −2 , indicating that interface recombination is not a dominated current transport mechanism in the nanowire diodes. CdS film diodes are simulated with acceptor traps and interface state density increased by two order of magnitude and shunt resistance reduced by one order of magnitude, indicating that high density of interface states and shunt paths occur in the CdS film diodes.
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This content will become publicly available on November 14, 2026
Propulsion of diodes in aqueous suspension under alternating-current or light stimulation
Micro- or nano-diodes suspended in water can propel controllably under alternating-current fields or light without the need for fuels such as hydrogen peroxide or urea. This makes them promising candidates for miniature motors in biomedical and other applications. However, the mechanisms underlying their propulsion remain unclear. This study investigates the propulsion of diodes floating in an aqueous solution at the millimeter scale, which facilitates observation of motion, allowing direct correlation with electrical measurements of device properties. We find that the diode’s propulsion is driven by forward current under an alternating-current field and by photocurrent under illumination. The velocity of propulsion scales linearly with the net current, with the rectified or photogenerated current creating an imbalance of ions at the ends of the diodes. This, in turn, generates an electric field that induces electrophoretic flow around the diode and propels the diode. Additionally, we assess the velocity of diodes intentionally damaged by high reverse bias and find that it decreases significantly because of the reduced difference between forward and reverse currents. These results suggest potential uses of diode propulsion for characterizing and separating bottom-up-grown nano-/micro- diodes based on their reverse-saturation current, as well as nanomotors formed from multiple-junction nanowire diodes that can self-propel in water under light.
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- PAR ID:
- 10647461
- Publisher / Repository:
- AIP Publishing
- Date Published:
- Journal Name:
- Journal of Applied Physics
- Volume:
- 138
- Issue:
- 18
- ISSN:
- 0021-8979
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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