Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 42: Devices

HL 42.4: Vortrag

Mittwoch, 18. März 2015, 10:15–10:30, EW 015

Growth of In_0.5Ga_0.5As/GaP quantum dots, manipulation of optical transitions by epitaxial means, and application in nano memory cells — •Gernot Stracke, Elisa Sala, Leo Bonato, Manuel Gschrey, Sven Rodt, Sören Selve, Tore Niermann, Christopher Prohl, Andrea Lenz, Holger Eisele, Andrei Schliwa, André Strittmatter, and Dieter Bimberg — Institut für Festkörperphysik, Institut für Optik und Atomare Physik und Zentraleinrichtung Elektronenmikroskopie, Technische Universität Berlin

InGaAs quantum dots (QDs) embedded in GaP have recently attracted attention for nano memory cells and monolithic integration of III/V-devices on silicon. A QD size- and strain- dependent transition from indirect to direct optical emission was predicted. Here we report on direct-gap In_0.5Ga_0.5As/GaP(001) QDs grown by metalorganic vapor phase epitaxy with strong optical emission. To initiate the three-dimensional growth mode of In_0.5Ga_0.5As on GaP, the GaP surface is covered with 2 monolayers (ML) of GaAs prior to InGaAs deposition. A second GaAs layer of 1-2 ML thickness grown on top of the QDs allows for improved strain relief of the QDs and results in a red-shift of QD luminescence from 722 nm to 843 nm, and an increase in luminescence intensity by more than one order of magnitude. The storage time of holes in In_0.5Ga_0.5As/AlP QDs is determined by deep level transition spectroscopy to 230 s at room temperature, the highest value hitherto measured in QDs. Thus, QDs in a (Ga,Al)P matrix represent promising candidates for future nano memory devices.