Electric field affects the charge state in ion-implanted Si-SiO2 structures

Using the method of depth profiling based on the measurement of high-frequency voltage-capacitance characteristics in an electrolyte-insulator-semiconductor structure in combination with the insulator layer etching, it was found that Ar ion implantation into the oxide film of a Si-SiO2 structure (oxide thickness, 250 nm) leads to the formation of positively charged (outer) and negatively charged (inner) layers in the SiO2 film beginning with an implanted ion dose of 10(14) cm(-2). The effect of an external electric field upon the charge state in these ion-implanted structures was studied. It was established that the negatively charged centers represent hole traps, which are recharged by the applied field to a neutral state. It is suggested that these centers are related to the appearance of nonbridging oxygen atoms as a result of the silicon oxide film reconstruction induced by the ion implantation to a dose exceeding 10(14) cm(-2). (C) 2001 MAIK "Nauka/Interperiodica".