Abstract
GaAs buffer layer in InAs/GaAs quantum dots (QDs) was investigated by Photoreflectance (PR) technique at 300 K. PR spectra obtained were compared with commercial GaAs sample PR spectra, and they were analyzed by using the derivative Lorentzian functions as proposed by Aspnes in the middle field regimen. PR spectra in InAs/GaAs QDs sample was attributed to the photoreflectance response in the GaAs buffer layer. Band bending energies were calculated for laser intensities from 1 mW to 21 mW. The photoreflectance comparative study in the samples was realized considering the difference in the parameters: electric field on the surface, broadening parameter, energy gained by photoexcited carriers due to the electric field applied, frequency of light and heavy holes and band bending energy values. The results suggest that the presence of InAs quantum dots increases the light and heavy holes frequencies and the band bending energy values; and decreases the electric field on the surface, the broadening parameter and the energy gained by photoexcited carriers. We found that InAs QDs presence modifies the surface electrical field around one order of magnitude in the GaAs buffer layer and this behavior can be attributed to surface passivation.
Highlights
It is known that PR spectra can be classified depending on the electric field strength in depletion region [24,28], andSelf-Assembled Quantum Dots (SAQDs) have been the appearance of Franz-Keldysh Oscillations (FKOs) in the PR spectrum indicates intensively investigated due to the interest from a medium field regimen
The optical properties of InAs/GaAs quantum dots (QDs) have been sharp Higher Holes (HH) and Light Holes (LH) transition investigated via photoluminescence (PL) and peaks can be observed after taking the fast fourier transform photoluminescence excited (PLE) techniques [20,21,22], but (FFT) to the FKOs line shapes [25]
InAs/GaAs QDs sample PR spectra were obtained and compared with a commercial GaAs sample PR spectrum, and they were analyzed by using the derivative Lorentzian functions as proposed by Aspnes in the middle field regimen
Summary
It is known that PR spectra can be classified depending on the electric field strength in depletion region [24,28], and. Self-Assembled Quantum Dots (SAQDs) have been the appearance of FKOs in the PR spectrum indicates intensively investigated due to the interest from a medium field regimen These spectra were fitted by using a fundamental physics point of view [1,2,3] and for their damped FKO above the gap originating from the epitaxial potential in technological applications [4,5,6,7], such as lasers GaAs surface. The signals under consideration in the measured PR device is the interaction between the density of surface traps spectra were GaAs band gap transition and higher-energy and free carriers, known as the trap-filling time (τ) [34,35], transitions associated to Franz-Keldysh Oscillations (FKOs). We discussed the buffer layer effect as host for InAs QDs
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