Erbium–silicon–oxide nano-crystallite waveguide formation based on nano-porous silicon

Abstract A new method is shown of the formation of a waveguide structure composed of erbium–silicon–oxide (Er–Si–O) nano-crystallites based on nano-porous silicon. A porous silicon (PS) double layered (core and clad) waveguide structure with a cross-section of semicircular shape was first formed by spatially selective anodic etching of an n-Si wafer in the dark. The core and clad PS layers consist is of different nanometer pore sizes. Next, Er ions were incorporated into pores by immersing the PS layers in an erbium-chloride/ethanol solution for 24 h. After drying, a two-step annealing was carried out to convert the Er-incorporated PS layers into Er–Si–O crystallites. The resulting samples showed a finely structured photoluminescence spectrum due to the 4f–4f inner shell transition of Er 3+ ions at room temperature which was characteristic of Er–Si–O crystallites.