Optical properties of zinc nitride thin films deposited by RF-sputtering

Recently, there has been a renewed interest in zinc nitride as there have reports that it can be converted to p-type ZnO:N by an appropriate heat-treatment in an oxygen atmosphere and consequently be used in transparent optoelectronic devices. In this work, zinc nitride thin films were deposited on unheated glass and silicon substrates by reactive RF-sputtering from a pure zinc target in an atmosphere of nitrogen and argon. The RF-power was varied from 50 W to 250 W and the deposition time from 5 minutes to 45 minutes. Their optical transmittance was measured in the wavelength range of 200 - 2500 nm. The as-deposited films were amorphous. The films deposited at RF-powers up to 150 where transparent with heir average transmission of 90% (Figure 1). Interference fringes were observed in the spectra which enabled the determination of the optical parameters of the films. On the other hand, the films deposited at high rf-powers or by using a mixture of argon and nitrogen (50%Ar, 50% N₂) were opaque suggesting that there rich in Zn. These results will be presented and discussed.