Photoluminescence of Ge islands grown by Ultra High Vacuum-Chemical Vapour Deposition on Si(100)

In this work different Ge on Si samples have been investigated with respect to their morphology and optical properties. Ge films were deposited on Si(100) by Ultra High Vacuum-Chemical Vapour Deposition from GeH4, at substrate temperature between 325-450°C. The films were without cap layer. Microscopic characterization showed that the Ge layers had a clustered morphology determined by the Stranski-Krastanov modality. These samples excited at 12 K by an Ar+ laser exhibited a photoluminescence (PL) band centered at 0.85 eV, which closely resembled the island-related feature observed for Ge dots embedded in Si. The PL spectra as a function of temperature is presented and discussed in terms of the morphological characteristics of the different samples.