Optics and Photonics Society of Iran

In this paper, the persistent photoconductivity effect of p-Si/SiGe/Si inverted modulation doped structure grown with molecular beam epitaxy method was  investigated.  A two dimensional hole gas  with areal density n_h was observed in the alloy layer off these structures which its density  can be changed by illumination with LED. The experimental results   of Hall effect measurement experiment indicated that  illumination of the sample by red light in temperature, leads to enhancing the two dimensional hole gas density and its electrical conductivity. This effect is a consequence of neutralizing the Si surface charges due to photo absorption in the Si cap and electron-hole pairs generation.