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In this paper we report a unique electrical response of ethanol-adsorbed ZnO films subjected to a constant potential difference. Current measurements were obtained in both dark and illuminated conditions. A significant delay in achieving saturation current was observed indicating a nonlinear and time varying effective resistance; a time-dependent equation describing this behavior was developed, allowing the calculation of a time constant for the transition regime. To determine the role of the surface properties in this behavior, microwave plasma was used to etch the ZnO film by varying degrees, resulting in an enhancement of the resistance switching for extended etching times.
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This content will become publicly available on July 1, 2026
In situ , simultaneous spectroscopic ellipsometry and quadrupole mass spectrometry studies of ZnO etching using Hacac and O2 plasma
The etching of ZnO thin films using acetylacetone (Hacac) doses with long exposure times, followed by purging and subsequent exposure to O2 plasma, is studied in a hot-wall reactor using simultaneous in situ spectroscopic ellipsometry and quadrupole mass spectrometry. The static exposure step results in the efficient consumption of Hacac. For each etch cycle, the O2 plasma plays a crucial role in removing unreacted Hacac from the ZnO surface, priming the surface for subsequent Hacac etching. This is confirmed by the production of CO2 during the O2 plasma pulse. The temperature window for etching is established as 220–280 °C with a maximum etch per cycle (EPC) of 0.15 nm/cy. Under these conditions, the Hacac pulse is 2 s long with a 30 s static hold step followed by 5 s O2 plasma step at 300 W power. Statistical analyses of etch data at the granularity level of each cycle reveal the importance of the static hold step in determining EPC. Arrhenius behavior of etching during the hold step reveals a piecewise linear trend with a low temperature (120–200 °C) activation energy (Ea) of 202 meV and a high temperature (200–320 °C) Ea of 32 meV. It is shown that saturation behavior in EPC is pulse time and static hold time dependent. Shorter Hacac pulses (≤1 s) demonstrate saturation behavior for static hold times ∼30 s, longer pulses of Hacac (≥2 s) show no saturation in EPC with static hold times up to 75 s.
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- PAR ID:
- 10615959
- Publisher / Repository:
- AIP Publishing
- Date Published:
- Journal Name:
- Journal of Vacuum Science & Technology A
- Volume:
- 43
- Issue:
- 4
- ISSN:
- 0734-2101
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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