Absorption and emission characteristics of mesa and ridge waveguide diodes made from strain adjusted SImGEn superlattice and SI/GE quantum well layers grown by MBE

摘要

We have fabricated mesa and ridge waveguide diodes from Si/Ge quantum well (QW) and short-period superlattice samples deposited by MBE on a (100) Si substrate. We have grown Si/Ge/Si$- 1$MIN@x$/Ge$-x$/ QW samples consisting of thin Ge wells where 20 MLs of Si are embedded in-between and followed by a SiGe layer elastically strained on a Si substrate as well as symmetrically strained on a strain symmetrizing buffer layer. We have also grown Si$-m$/Ge$-n$/ short-period, strained layer superlattices consisting of N periods of (m $PLU n) monolayers per period which are deposited on a strain adjusting buffer layer. The edge emitting ridge waveguide diodes fabricated from this material with standard semiconductor processing techniques were polished on the $LFAN@110$RTAN side faces and etched to a height of roughly 1.0 $mu@m with lateral dimensions of roughly 100 $mu@m width $MUL 3 mm length. Also circular mesa diodes were fabricated with the same height and varying diameters from 100 $mu@m to 800 $mu@m and were provided with a metal ring contact on top defining the illumination window. Photocurrent and electroluminescence signals at h$nu approximately 0.8 eV were detected at room temperature from QW samples. The emission characteristics as a function of strain and composition of the SLS and QW layers are discussed.