Low-energy electron diffraction from heated porous silicon surfaces

We have found that low-energy electron diffraction patterns can be obtained from porous silicon samples made with various silicon orientations, resist ivities and anodisation treatments, after specimens have been heated in an ultra-high vacuum to around 850 degrees C for (100) samples and 950 degrees C for (111) samples. The results show that at least some of the surfaces o f porous silicon are, in ail cases studied, parallel to the original surfac e before anodising. The (100) surfaces show a clean surface 2 x 1 reconstru ction, but fractional order spots appear only as streaks in the (I Il) surf ace patterns. For significant portions of samples, the underlying silicon c rystal lattice is continuous to the very top of the porous region. (C) 2000 Elsevier Science B.V. All rights reserved.