Photoluminescence and electron paramagnetic resonance studies of defect centers in porous silicon

Photoluminescence (PL) and electron spin resonance (ESR) spectrometers were exploited to study the Pb defect centers in porous silicon (PS) under various heat treatments. The breaking of Si–Hx and Si–O–H bonds in PS by thermal annealing changes the emission wavelength and increases the recombination centers resulting in degrading the PL intensity. Four kinds of dangling bonds on interfaces of silicon (1 1 1), (1,−1,−1), (−1,1,−1), and (−1,−1,1) faces and SiO2 with C3V symmetry were identified. The skeleton structure of PS collapsed under thermal annealing. Annealing in hydrogen gas, which is controvertible to the pervasive anticipation, cannot passivate the dangling bonds introduced at high temperatures.