Structural change in p-type porous silicon by thermal annealing

The morphological change of p-type porous silicon during annealing has been investigated. The x-ray diffraction (XRD) pattern was composed of a sharp Bragg reflection peak and a diffuse scattering. The diffuse scattering is n ot related to the presence of the amorphous phase. The shape of the XRD pat tern started to change at an annealing temperature as low as 400 degreesC, and the 2 theta angle of the sharp peak varied at a temperature as low as 3 50 degreesC. These changes at low temperatures seem to be closely related t o the desorption of hydrogen and the resultant change of the dangling bond density in porous silicon. The molecular orbital calculations also support the participation of dangling bonds in the structural reorganization in the surface region. (C) 2001 American Institute of Physics.