Observation of (100) surfaces in p-type porous silicon by electron paramagnetic resonance

Abstract

Native oxide interfaces in stain-etched p-type porous Si obtained by room-temperature oxidation of vacuum-annealed (T⩽650°C) layers have been studied by electron paramagnetic resonance. In addition to the previously evidenced (111) interfaces we have identified (100) interfaces, revealed by the presence of the specific Pb1 defects. The (100) interfaces are only observed in the 650°C annealed samples. The 650°C annealing stage is associated with a particular hydrogen effusion peak and the disappearance of the SiH and SiH2 stretching bands. The oxidation of the (111) surfaces proceeds already for lower annealing temperatures (T⩽300 °C). In the 605 °C annealed sample, the (100)/(111) interface ratio is estimated to 2/1 and the total oxidised surface to ≈36%.