| AVS 55th International Symposium & Exhibition | |
| Thin Film | Wednesday Sessions |
| Session TF-WeA |
| Session: | Computational and Experimental Studies of Thin Films |
| Presenter: | C. Venkatasubramanian, The Pennsylvania State University |
| Authors: | C. Venkatasubramanian, The Pennsylvania State University M.W. Horn, The Pennsylvania State University S. Ashok, The Pennsylvania State University |
| Correspondent: | Click to Email |
Vanadium oxide (VOx) thin films find extensive use in room-temperature bolometers for IR imaging. It is desirable to control and modify the electronic properties of the material with treatments such as ion implantation and thermal annealing. In this work, we report on the modification of structural and electrical properties of VOx thin films used in microbolometers. VOx films of varying compositions were deposited by pulsed dc reactive sputtering of a vanadium target under different oxygen flow rates. The as-deposited resistivities of the films ranged from 0.1 ohm-cm to 100 ohm-cm and the temperature coefficient of resistance (TCR) values varied from -1.1 to -2.7 % K-1. VOx films used in microbolometer applications need to have a high TCR (> 2 % K-1) and low resistivity values (1 -10 ohm-cm). But, typically, a high TCR is associated with a high resistivity. Hence ion-implantation followed by annealing was performed in order to examine trade-off between TCR and resistivity. Two species - Hydrogen (active) and Helium (inert) were chosen for implantation. Hydrogen is an active species well known for passivating defect states in a wide variety of electronic materials. Helium is an inert species and was chosen mainly to study the effects of bombardment on the film. The implanted films were annealed in an inert atmosphere to allow for redistribution of atoms, and then characterized by current-voltage measurements over a wide temperature range. The effect of thermal annealing alone was evaluated separately by annealing the unimplanted samples. In both cases, an order of magnitude change in resistance, and significant variations in TCR were observed. Further characterization has been done by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) to correlate these resistivity changes with the structure of the films.