1.55 μm emission from InAs quantum dots grown on GaAs.

We report a comparative study on the growth of InAs quantum dots (QDs) on GaAs by metalorganic chemical vapor deposition using triethylgallium (TEGa) and trimethylgallium (TMGa) for the GaAs cap layer. QDs exhibit 1.3 μm photoluminescence (PL) at room temperature, as the GaAs cap layer is directly grown on the QDs. The PL emission can be extended to 1.49 μm when an In_0.25Ga_0.75As overgrown layer is inserted between the cap layer and the InAs QDs. The use of TMGa or TEGa for the growth of the GaAs cap layer is essential for a further increase in the emission wavelength of the InAs QDs. Strong PL emission at 1.55 μm with a linewidth of 28 meV can be obtained as the GaAs cap layer is grown by TEGa, while the optical properties degrade severely when using TMGa. [ABSTRACT FROM AUTHOR]