LPE growth of quantum dot nanostructures for mid-infrared sources
It is generally accepted that liquid phase epitaxy (LPE), which is an equilibrium growth technique, produces epitaxial material of the highest crystalline perfection containing few point defects and impurities and is therefore well suited to the fabrication of optoelectronic devices. The combination of high quality epitaxial layers and the advantages afforded by quantum well (QW) or quantum dot (QD) structures is very attractive for the development of mid-infrared light sources. However, for the growth of quantum structures, precise thickness control is of paramount importance, and a high growth rate is not advantageous. We are studying the growth of quantum well and quantum dot structures using a rapid slider modification of the LPE technique where the melt is quickly wiped across the substrate. We have successfully used this technique to produce QD LEDs which operate in the mid-infrared.
Fig. 1 The electroluminescence emission spectrum obtained from an InAsSb quantum dot LED measured at 4 K using 250 mA injection current. Inset shows photoluminescence emission from the active layer.
Fig. 2 The AFM image of InSb QDs grown on GaAs(100).
(a) Grown at 330 °C with 16 °C supercooling,
(b) The same region at low magnification showing the large dots.