Hydrostatic pressure effects on the porous silicon luminescence

Abstract Recent high pressure measurements on different types of porous silicon (PS) samples have provided very interesting information on the variation and the stability of the related visible luminescence. It is shown that this luminescence still exists in samples which have undergone the diamond-β-Sn phase transition and persists in those samples when they are recovered at atmospheric pressure in the BC8 phase. Different techniques, including Raman and X-ray measurements, have been used to determine the structure of the silicon on these luminescent samples. They provide upper bounds on the degree of the phase transformation which will be discussed. Since the results are not qualitatively dependent on the way the samples are prepared, it is concluded that the observed effects are characteristic of the PS luminescence and that its existence cannot be related to the diamond phase of the silicon. Therefore this luminescence is believed to originate more likely from the surface of the silicon than from the bulk part.