Influence of HF etching on the velocity of surface acoustic phonons in air-aged porous silicon layers

摘要

Brillouin light scattering spectroscopy has been used to measure surface acoustic phonon velocities on six-month aged layers of porous Si formed from p~+ -type [111]-oriented crystalline Si substrates. The as-prepared porosities were 25-29/100 and spectra were recorded both prior to and following a 10 s dip in 5/100 aqueous HF The velocities for the dipped samples were 3-6/100 lower than those of the corresponding pieces which were not dipped. This difference is attributed to the presence of native oxide films on the surfaces of the air-stored samples which are removed by the HF dip.