Formation of Ge quantum dots on boron-reconstructed surface/Si(111)

Uniformity and arrangement of Ge quantum dots were investigated on B-reconstructed surface of Si(111). B coverage was varied from 0 to 0.35 ML on the Si(111) 7×7 surface, and Ge dots were formed after formation of B-reconstructed surface. 8 ML Ge was deposited on this surface and annealed at 500 °C. The size and density of Ge dots was analyzed with TEM and AFM. Optical properties of Ge dots were investigated by Photoluminescence (PL) measurement. When there was no B coverage, the lateral size and height of Ge dots were 50 and 10 nm, respectively, without uniform distribution. When an ordered √3×√3 R30°-B surface was formed, quite uniform Ge dots were formed with 35 nm lateral size and 7 nm in height, with an obvious array in one direction. Moreover, a strong PL spectrum was observed from these Ge dots at 4 K.