Low Temperature Radiation Response of Al2O3 Gate Insulators

The response of Al2O3 MIS capacitors to steady state (Co60) and pulsed high-energy (13-MeV e-) ionizing radiation was measured at 297 and 80 K as a function of applied bias and dose. The radiation sensitivity of the Al2O3 at 80 K was found to be little altered from its room temperature value and was significantly reduced from that of comparable SiO2 gate insulator materials measured under similar conditions. Experimental evidence suggests that the primary mechanism for the superior performance of Al2O3 at 80 K is rapid transport of most of the radiation generated carriers out of the oxide layer. The injection of electrons into the Al2O3 under bias stress was also measured at 297 and 80 K, and was found to be drastically slowed at the lower temperature. As a consequence of its superior performance under irradiation at 80 K, Al2O3 may be an attractive alternative to SiO2 gate insulator materials in critical low temperature applications.