Shapes, dimensions, arrangements and the microstructure of self-assembled island s fabricated by low-pressure chemical vapour deposition (LPCVD) of Ge at 700℃ o nto Si(110) substrates have been investigated for different nominal Ge coverage by transmission electron microscopy (TEM) of plan-view and cross-section specime ns and have been compared with photoluminescence (PL) measurements of Si-capped layer samples. The transition from the 2-dimensional layer to the 3-dimensional island growth mode takes place for a Ge deposition of nominally less than 2 mono layers. Upon this transition, many coherent islands and few larger islands with extended defects are observed. The coherent islands possess a dome-like shape an d lateral sizes up to 130nm. Photoluminescence spectra show island-related peaks whose energy positions are shifted towards lower energy with higher Ge coverage . Shapes, dimensions, arrangements and the microstructure of self-assembled island fabricated by low-pressure chemical deposition (LPCVD) of Ge at 700 ° C o nto Si (110) substrates have been investigated for different nominal Ge coverage by transmission electron microscopy ( TEM) of plan-view and cross-section specime ns and have been compared with photoluminescence (PL) measurements of Si-capped layer samples. The transition from the 2-dimensional layer to the 3-dimensional island growth mode takes place for a Ge Following this transition, many coherent islands and few larger islands with extended defects were observed. The coherent islands have a dome-like shape an lateral size up to 130 nm. Photoluminescence spectra show island-related peaks whose energy positions are shifted towards lower energy with higher Ge coverage.