Effects of hydrogen related defects on the electrical properties of thin
film MgO
Björn Víkingur Ágústsson
Science Institute, University of Iceland,
Dunhaga 3, IS-107 Reykjavik, Iceland
Abstract
The effects of hydrogen impurities on the electrical properties of thin
film magnesium oxide (MgO) was investigated. Thin MgO films
were grown in a reactive magnetron sputtering discharge while
hydrogen was added to the growth environment. Nuclear resonance
reaction analysis (NRRA), X--ray diffraction (XRD), and impedance
spectroscopy measurements were performed on the samples.
The NRRA measurements showed no increase in the hydrogen content of the
grown MgO films, as the hydrogen partial pressure was increased in the
growth chamber. This may indicate that the amount of hydrogen when the
base pressure is in the vicinity of 1$\times$10$^{-8}$
Torr, is sufficient to saturate the MgO crystal. The X--ray
diffraction measurements showed polycrystalline structure of the
grown films. The MgO films had both (2 0 0) and (2 2 0) crystal
planes. The impedance spectroscopy measurements indicated
significant electrical conduction in some of the samples. However, the
conduction seems to be unrelated to hydrogen flow in to the
growth chamber while growth takes place. The large effective size of the
capacitors is believed to be the most likely cause for defects at the
interface between the Cr$_{x}$Mo$_{1-x}$ and the MgO films. Storing the
MgO films in ambient air at room temperature for one
month resulted in much lower resistance of the films. The film
properties were not recovered by annealing.