ATOMIC-FORCE MICROSCOPY STUDIES ON VARIOUS TYPES OF PHOTOLUMINESCENT POROUS SILICON

The structural characteristics of anodically-etched porous silicon (PS ) layers emitting at different energy levels and with various luminesc ence fatigue strengths, recently classified into types A, B and C are compared using atomic force microscopy. Quantum-size micro-particles h ave been observed in type A PS within amorphouslike contrast, but only fairly rough amorphous grain-like structures have been observed in ty pe B and C PS. Drastic quenching of photoluminescence in the PS layer after deposition of a capping layer of amorphous silicon is also repor ted.