In this article we study the electroluminescence of p-i-n diode structures
with Ge dots consisting of coherent three-dimensional small (pyramids) and
larger (dome) islands. The Ge dots are formed through strain-induced island
ing. The diode structures, including one layer with Ge dots, were deposited
on Si mesas with variable areas in order to study the influence of limited
area deposition on self-assembling. It was observed that the reduction of
deposited area improves island uniformity. The combined analysis of island
distribution and electroluminescence spectra has lead to the conclusion tha
t domes in small diodes have a smaller Si content or are less relaxed than
domes in larger diodes. The diodes are found to emit up to room temperature
near the optical communication wavelength of 1.3 microns. (C) 2000 America
n Institute of Physics. [S0021-8979(00)04610-7].