Abstract
The changes in the free-carrier concentration in polycrystalline ZnO films during exposure to H 2 and O 2 plasmas were studied using in situ attenuated total reflection Fourier transform infrared spectroscopy. The carrier concentration and mobility were extracted from the free-carrier absorption in the infrared using a model for the dielectric function. The electron density in polycrystalline zinc oxide films may be significantly increased by > 10 19 cm -3 by brief exposures to hydrogen plasma at room temperature and decreased by exposure to O 2 plasmas. Room-temperature oxygen plasma removes a fraction of the H at donor sites but both elevated temperatures (∼225 °C) and O 2 plasma were required to remove the rest. We demonstrate that combinations of O 2 and H 2 plasma treatments can be used to manipulate the carrier density in ZnO films. However, we also show the existence of significant drifts (∼15%) in the carrier concentrations over very long time scales (hours). Possible sites for H incorporation in polycrystalline films and reasons for the observed carrier-concentration changes are proposed.
| Original language | English (US) |
|---|---|
| Article number | 043522 |
| Journal | Journal of Applied Physics |
| Volume | 97 |
| Issue number | 4 |
| DOIs | |
| State | Published - Feb 15 2005 |
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ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)
- Physics and Astronomy(all)
Cite this
Infrared detection of hydrogen-generated free carriers in polycrystalline ZnO thin films. / Wolden, Colin A.; Barnes, Teresa M.; Baxter, Jason B.; Aydil, Eray.
In: Journal of Applied Physics, Vol. 97, No. 4, 043522, 15.02.2005.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Infrared detection of hydrogen-generated free carriers in polycrystalline ZnO thin films
AU - Wolden, Colin A.
AU - Barnes, Teresa M.
AU - Baxter, Jason B.
AU - Aydil, Eray
PY - 2005/2/15
Y1 - 2005/2/15
N2 - The changes in the free-carrier concentration in polycrystalline ZnO films during exposure to H 2 and O 2 plasmas were studied using in situ attenuated total reflection Fourier transform infrared spectroscopy. The carrier concentration and mobility were extracted from the free-carrier absorption in the infrared using a model for the dielectric function. The electron density in polycrystalline zinc oxide films may be significantly increased by > 10 19 cm -3 by brief exposures to hydrogen plasma at room temperature and decreased by exposure to O 2 plasmas. Room-temperature oxygen plasma removes a fraction of the H at donor sites but both elevated temperatures (∼225 °C) and O 2 plasma were required to remove the rest. We demonstrate that combinations of O 2 and H 2 plasma treatments can be used to manipulate the carrier density in ZnO films. However, we also show the existence of significant drifts (∼15%) in the carrier concentrations over very long time scales (hours). Possible sites for H incorporation in polycrystalline films and reasons for the observed carrier-concentration changes are proposed.
AB - The changes in the free-carrier concentration in polycrystalline ZnO films during exposure to H 2 and O 2 plasmas were studied using in situ attenuated total reflection Fourier transform infrared spectroscopy. The carrier concentration and mobility were extracted from the free-carrier absorption in the infrared using a model for the dielectric function. The electron density in polycrystalline zinc oxide films may be significantly increased by > 10 19 cm -3 by brief exposures to hydrogen plasma at room temperature and decreased by exposure to O 2 plasmas. Room-temperature oxygen plasma removes a fraction of the H at donor sites but both elevated temperatures (∼225 °C) and O 2 plasma were required to remove the rest. We demonstrate that combinations of O 2 and H 2 plasma treatments can be used to manipulate the carrier density in ZnO films. However, we also show the existence of significant drifts (∼15%) in the carrier concentrations over very long time scales (hours). Possible sites for H incorporation in polycrystalline films and reasons for the observed carrier-concentration changes are proposed.
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U2 - 10.1063/1.1851599
DO - 10.1063/1.1851599
M3 - Article
VL - 97
JO - Journal of Applied Physics
JF - Journal of Applied Physics
SN - 0021-8979
IS - 4
M1 - 043522
ER -