Heat treatment effect on porous silicon

The effect of a typical pre-epitaxial heat treatment in H2 atmosphere at 1000–1200°C on porous silicon (PS) was investigated. As-grown PS possesses the monocrystalline structure of the original n+-Si substrate with a relative lattice deformation up to 4 x 10−4, a developed system of vertical pores 3–16 nm in diameter and a specific surface area of about 100–200 m2 cm−3. The heat treatment of the PS results in the rearrangement of its crystalline structure, the modification of its lattice deformation and a decrease in its specific surface area to a value of 10m2 cm−3. Simultaneously the pores are essentially modified in form, size and quantity. The phenomena described can be explained as the result of the sintering of PS under the heat treatment.