Control of performance and stability of thin film diodes using chromium nitride contacts

We show that reactively sputtered chromium nitride thin films can be used as bottom contact layers in amorphous silicon rich silicon nitride thin film diodes. In common with most amorphous thin film devices the electrical characteristics of these diodes have been found to drift during use. The slope of the thin film diode current–voltage characteristic and its stability can be controlled through manipulation of the chromium nitride deposition parameters. Increasing the nitrogen partial pressure during deposition of chromium nitride causes the nitrogen content of the deposited layer to increase and the oxide growth on the surface of the chromium film to be reduced. This in turn reduces the tunnel barrier and trap density at the metal silicon nitride interface and steepens the current–voltage characteristic. The field through the device can then be reduced below a critical point where it does not affect stability.