Conditions of elaboration of luminescent porous silicon from hydrogenated amorphous silicon

We present a systematic study of the preparation and properties of porous silicon obtained by anodic etching of device-grade hydrogenated amorphous silicon. Highly luminescent porous material is produced from boron-doped films and, by hole injection, from undoped films. A striking difference between amorphous and crystalline Si lies in an electrochemical instability which limits the maximum obtainable thickness in porous material. The luminescence mechanism for porous a-Si:H appears to be markedly different from that of its crystalline counterpart.