Enhanced conductivity of zinc oxide thin films by ion implantation of hydrogen atoms

Abstract

Enhancement of the conductivity of zinc oxide through doping with hydrogen atoms was examined by using ion implantation of highly resistive thin films deposited by rf magnetron sputtering at room temperature. With a doping of 1×1017 atoms cm−2, the conductivity after annealing at 200 °C in an N2 atmosphere at 1 atm rose from the initial 1×10−7 Ω−1 cm−1 to 5.5×102 Ω−1 cm−1.

Hydrogen as a Cause of Doping in Zinc Oxide

“…Mollwo [11] observed an increase in the conductivity of ZnO crystals exposed to hydrogen at temperatures above 200 ± C. The increase in the conductivity was demonstrated to be due to indiffusion of hydrogen, for which an activation energy of 0.91 eV was measured [11,12]. An increase in conductivity upon exposure to H 2 was also observed by Baik et al [14], and by Kohiki et al [15] who introduced hydrogen by proton implantation followed by annealing at 200 ± C. All of these experimental results indicate that introducing hydrogen into ZnO does not result in a reduction of the conductivity, which is the expected behavior for hydrogen in other semiconductors. Instead, H shows strong behavior as a donor, consistent with the calculations reported here.…”

Effects of Protium Introduction on Electrical and Optical Properties of Tin-Germanium Oxide Thin Films

“…There are some reports on the effects of hydrogen ion implantation into Zn oxide films and Ge-Cd oxide films. [10][11][12] They confirmed that the hydrogen implantation improved the electrical conductivity of the oxides. The protium introduced into the oxides, however, sometimes gives coloration to the oxides.…”

Remote hydrogen plasma doping of single crystal ZnO

“…Similarly, theory [1][2][3] suggests hydrogen is a shallow donor impurity rather than a compensating center, a prediction supported by a number of spectroscopic studies. 4 -14 Some electrical measurements [12][13][14][15][16][17][18] are also consistent with H donor character, although the polycrystalline samples, direct plasma exposure, or the ion implantation involved may introduce additional complications. This letter presents strong transport and spectroscopic evidence in favor of the hydrogen shallow donor hypothesis.…”