Effect of interface fields on the piezoelectric response of aluminum nitride thin films

Group III-Nitride wide bandgap semiconductors have attracted much attention in the optoelectronic and electronic research areas recently. III-Nitride semiconductor materials are attractive materials for use in optoelectronic and high speed electronics devices because they are direct bandgap semiconductors and the bandgap can be varied over a wide range. It has also been shown that the III-Nitride group of materials function exceptionally well in harsh environments. The piezoelectric properties of the III-Nitride material system have been studied and several of the III-Nitride compounds have been found to have non zero piezoelectric coefficients. This work shows that the observed piezoelectric coefficient of Aluminum Nitride (AlN) is directly related to the metal used as the topside contact. The data and preliminary analysis presented here indicate that AlN cannot be treated as an insulating material and must be treated as a semiconductor in order to model its piezoelectric behavior.