Aluminum Nitride Thin Films for Pyroelectric Detection

A pyroelectric detector is a class of thermal detector for which there is a change in spontaneous polarization. Absorption of infrared radiation in the sensing layer of pyroelectric detector causes a change in temperature and hence changes in spontaneous polarization which finally generates a voltage. The objective of this work is to deposit and characterize thin films of ${Al}_{x}N_{y}$ for using them as pyroelectric material. Capacitors of ${Al}_{x}N_{y}$ thin films with Au electrodes were designed using Intellisuite software. Capacitors of various sizes were fabricated. The diameter of the electrodes for capacitor was varied between 400 $\mu $m to 1100 $\mu $m with 100 $\mu $m increment. The distances between two electrodes were varied between 400 $\mu $m to 1100 $\mu $m with 100 $\mu $m increment as well. On a 3 inch diameter cleaned quartz wafer, 20 nm thick Ti adhesion layer was deposited followed by a 100 nm thick Au layer. On top of this Au layer, 100 nm ${Al}_{x}N_{y}$ thin film was deposited. Finally, 100 nm thick Au layer was deposited and lifted off by conventional photo lithography to form the electrodes of capacitors. All the layers were deposited by radio frequency sputtering at room temperature. Morphology and electro-optical properties for ${Al}_{x}N_{y}$ thin films are now being investigated in the laboratory.