Optical Properties of InAs Self-Assembled Quantum Dots with Different InGaP Cladding Layer
Date Issued
2005
Date
2005
Author(s)
Lu, Yi-Bin
DOI
en-US
Abstract
The optical properties are studied with temperature dependent photoreflectance (PR) and photoluminescence (PL) experiments on InAs/GaAs quantum dot (QD) structures. The samples (Sm, Sc, and St) are grown by the gas-source molecular-beam epitaxy in the Stranski–Krastanov growth mode on an n+-doped GaAs (100) substrate and three multi-QD-stack lasers structure are deposited with different lattices InGaP cladding layer. Three QD samples with lattice-matched (Sm), compressive-strained (Sc) and tensile- strained (St) for the cladding layer were grown, and the later two QDs samples have the higher transition energy of the luminescence. Therefore, we could realize the effect of strain field reducing to different lattices cladding layer.
At room temperature, the major peaks in the PL spectra of the QD samples are 0.989eV for Sm, 1.004eV for Sc, and 0.998eV for St, respectively. Two peaks with long-tail on high energy portion are observed in PL spectra and integrated intensity is also discussed. Therefore, the thermionic emission plays important roles in the PL quenching. To determine the mechanism of the carriers in QDs, state filling experiments are carried out and verify the second group of InAs QDs.
From the PR experiments, optical transitions originated from the InAs QDs are observed. Transition energies of the ground state and excited states are verified. The temperature dependence transition energies following the Varshni’s semi-empirical formula was attributed to the dilation of lattice and electron-lattice interaction. The results from PL and PR spectra reveal that size and uniformity of InAs/GaAs QDs are affected by InGaP cladding layers.
In order to determine the transition energies observed from the temperature dependent PL and PR experiments, the AFM images have been carried out to estimate the diameters and heights roughly of the samples for theoretical calculations of the InAs/GaAs single QD with the truncated pyramidal shape. Consequently, the theoretical calculations of the InAs/GaAs single QD with the truncated pyramidal shape are carried out the ground state energy transition of InAs QD and verify that the effect of strain reducing to the mismatch of the cladding layer is lower than the effect reducing to the size distribution for the transition energy feature.
Subjects
銦化鎵
量子點
夾層
調制光譜
InAs
quantum dot
cladding layer
photoreflectance
SDGs
Type
thesis