Defect centers and changes in the electrical characteristics of Al/n-type Si Schottky diodes induced by hydrogen-ion implantations.

Abstract

Hydrogen-ion implantation was carried out on Al/n-type Si Schottky diodes. Following annealing at 200 \ifmmode^\circ\else\textdegree\fi{}C, the changes in electrical characteristics observed by the current-voltage and capacitance-voltage measurements upon implantation reverted to the preimplant cases. Hydrogen depth profiling revealed the accumulation of hydrogen near the Al/Si interface following the ion implantation. No significant changes in the hydrogen concentration or the redistribution of the hydrogen were observed following the heat treatment. Deep-level transient spectroscopy measurements indicated that the signals from two deep-level electron traps created upon implantation were drastically reduced upon 200 \ifmmode^\circ\else\textdegree\fi{}C annealing. These observations demonstrate that hydrogen passivates its own damage, thus resulting in the recovery of electronic transport across the metal-semiconductor junction upon low-temperature heat treatment. Moreover, deep-level transient spectroscopy measurements suggested that the defect centers in the depletion region have more likely negative or possibly neutral signatures rather than positive signatures, as has been previously speculated. Capacitance-voltage measurements performed on the diode showed a reduction of the capacitance following the implantation. This reduction of the capacitance could be interpreted as due to donor compensation by the negative charge center, thus resulting in a widening of the depletion region.