| Abstract [eng] |
Self-assembled InAs quantum dots (QDs), whose intersublevel transition energies lie in the mid- and far-infrared spectral range (3–25μm), have attracted particular interest as active elements of infrared photodetectors. This interest is mainly due to intriguing atomic-like quantum confinement and unique optical and electronic properties of QDs. Moreover, QD electronic structure can be adjusted by varying the dots size and shape or their environment. These features make QDs to be of importance in creation of photoelectronic devices with a desired spectral range. The dissertation is concerned specifically with molecular beam epitaxy grown InGaAs QD structures with: -- InAs QD stacks embedded in GaAs matrix and GaAs/AlAs superlattice (SL), or alternatively InAs/GaAs QD-SL structures with and without AlAs barriers between the dot layers; -- InAs QDs with and without InGaAs strain-reducing layers, embedded within GaAs/AlAs quantum wells; -- columnar InGaAs QDs, also referred to as quantum rods (QRs) or quantum posts, of different morphology. (The quantum confined structure consists of vertically oriented InGaAs QRs immersed in a two-dimensional InGaAs layer). These QD structures were studied by modulated reflectance and photo- luminescence spectroscopies to reveal their optical properties and the full- extent of electronic structure. Experimental data were interpreted by numerical (nextnano3 software) and analytical (algorithm developed) modelling. |
