Hot-electron-induced defects at the Si-SiO2 interface at high fields at 295 and 77 K
Abstract
Fowler-Nordheim tunneling electron injection is performed at 295 and 77 K in metal-oxide-semiconductor capacitors. In both cases the positive charge generated at the Si-SiO2 interface is found to be the ''anomalous'' positive charge related to the slow states. At low temperature this charge is created at a faster rate than at 295 K for both positive and negative polarity. Its saturated density, on the contrary, strongly depends on the polarity of the applied bias voltage at low temperature, being much smaller during injection at positive bias. Fast and slow states appear only after the sample is heated to room temperature. While interband impact ionization is ruled out as a possible generation mechanism, the results are consistent with the idea that the hot injected electrons lose their energy at the anode-SiO2 interface by emitting an unidentified species which is responsible for the generation of the interfacial damage. A field- and temperature-activated migration of the positive defects from the sites of formation to the interface must occur before slow and fast states are observed. The correlation between slow states and hole traps is discussed.