We report structural and photoluminescence (PL) investigations of self-asse
mbling typically 100 nm lateral size Ge islands and 10 nm size C-induced Ge
quantum dots in Si. The different recombination pathways are discussed for
single and stacked dot layers. The aim is to evaluate different ways of us
ing self-assembling quantum structures for Si-based emitters in the wave le
ngth range of 1.3 to 1.55 mu m The pre-growth of a small fraction of a mono
layer C on Si(100) introduces nucleation centers for the subsequent formati
on of Ge islands which results in the formation of a high density of extrem
ely small 10 nm size quantum dots. PL-studies indicate a spatially indirect
radiative recombination mechanism with the no-phonon line strongly dominat
ing. For larger stacked Ge islands with 13 nm thin Si spacer layers, we obs
erve a significantly enhanced Ge dot-related PL signal up to room temperatu
re at 1.55 mu m wave length. This is attributed to a spatially indirect tra
nsition between heavy holes confined within the compressively strained Ga:
dots and two-fold degenerated Delta state electrons in the tensile strained
Si spacer layers between the stacked Ge dots. In the second part we presen
t the preparation and I-V characteristics of Si/SiGe/ Si p(+)/i/n(+) Esaki
diodes. The incorporation of a maximum amount of Ge within the i-zone incre
ases the interband tunneling probability and thus, gives rise to an increas
ed peak current density of about 3 kA/cm(2) and a peak to valley current ra
tio of 4.2 at room temperature. The further increase of Ge content by incor
poration of self assembling Ge islands within the intrinsic cone of the dio
de is discussed. (C) 2000 Elsevier Science S.A. All rights reserved.