STUDIES OF TRAPS IN Al2O3 FILMS.
Abstract
Measurements of photocurrent as a function of photon energy were performed on thin film metal-insulator-metal samples at liquid-nitrogen temperature, at room temperature, and at 97C to determine the effect of temperature on the scattering parameters and barrier shapes. Evaporated aluminum films were electrochemically anodized, and aluminum or gold top electrodes were evaporated onto them. Patterns were then formed by photolithographic techniques. Chopped-light and phase-sensitive-detection techniques were used for the photomeasurements. Evaluation of the photomeasurements indicated that the main effect of temperature variation is a change in the barrier shape. The barrier height in the middle of the insulating film changes very drastically (approximately 0.5 EV larger at liquid-nitrogen temperature than at 97C), while the barrier heights at the interfaces change very little (approximately 0.1 EV). The change in barrier shape can be explained by an increased space charge due to trapping of electrons in the insulating thin film at low temperatures. It was found previously that the scattering of electrons within the insulating film can be measured most accurately if the electrons encounter a retarding field; that is, if the applied voltage is less than the difference of the two barrier heights. The present photomeasurements indicate that under such conditions, the slopes of the photoresponse, and hence the scattering of electrons within the insulator, are independent of the temperature. These findings agree with theory. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1970
- Accession Number
- AD0709217
Entities
People
- Charles R. Young
- Fritz L. Schuermeyer
Organizations
- Air Force Research Laboratory