Detection of the third transition of InAs/GaAsSb quantum dots

作者：Kim Yeongho; Ban Keun Yong^*; Dahal Som N; McFelea Heather; Hon**erg Christiana B

来源：Journal of Ceramic Processing Research, 2016, 17(4): 369-372.

• Epitaxial layers
• III-V semiconductor materials
• Photovoltaic cells
• Semiconductor nanostructures

The optical properties of InAs quantum dots (QDs) embedded in GaAs0.92Sb0.08 barriers have been studied. The samples studied consist of 20 multiple layers of InAs QDs embedded in GaAs0.92Sb0.08, with each QD/barrier system separated by a 100 nm GaAs spacer. No appreciable changes in the QD properties, such as size, shape, and density, are observed by Scanning Transmission Electron Microscopy (STEM) images. The delta-doping plane beneath the InAs QDs allows the occupancy of the QD electronic sub-band states to be controlled. Low temperature (77 K) Fourier Transformation-Infrared Spectroscopy (FT-IR) results, using a multiple internal reflection (MIR) technique to enhance the optical path length, show intersubband absorption in the InAs QD area. The broad peak observed around 240 meV corresponds to the energy separation between the electron ground state and the continuum state of the QDs. Another broad peak around 440 meV is ascribed to a transition between a deep level and shallow donor level due to delta-doping as the signal increases as the doping density increases. Band structure calculations using an eight band k center dot p method are used to confirm the experimental results observed here.

• 出版日期2016-4