In this work, the influence of the surface depletion layer on the formation of a two-dimensional electron gas in AlGaAs/GaAs modulated doped heterostructures is studied. The authors explore a method for estimating the depletion region inside of the GaAs-based heterostructures by using the longitudinal optical and L- amplitude modes observed in Raman spectra, which are supported by the modeling results. The authors found that the position of the topmost doping layer changes the electron distribution in the heterostructure and decreases the influence of the depletion layer. Similar effects are perceived when an optimized solution of (NH4)2SX and isopropanol is employed. The authors present a method to evaluate the formation of a double two-dimensional electron gas in a heterostructure by the adequate use of modulation line in the photoreflectance spectroscopy.

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The high order self-organization of quantum dots is demonstrated in the growth of InAs on a GaAs(631)-oriented crystallographic plane. The unidimensional ordering of the quantum dots (QDs) strongly depends on the As flux beam equivalent pressure (P As ) and the cation/anion terminated surface, i.e., A-or B-type GaAs(631). The self-organization of QDs occurs for both surface types along ½ 113, while the QD shape and size distribution were found to be different for the self-assembly on the A-and B-type surfaces. In addition, the experiments showed that any misorientation from the (631) plane, which results from the buffer layer waviness, does not allow a high order of unidimensional arrangements of QDs. The optical properties were studied by photoluminescence spectroscopy, where good correspondence was obtained between the energy transitions and the size of the QDs.

Ternary III-N-V semiconductor alloys are interesting and complex materials. GaNAs is one such material that has been studied extensively; however, the accurate determination of the N content within this material in which the growth conditions significantly increases the amount of interstitial N has not yet been reported. To address this problem, GaNAs layers (100 nm) were prepared using molecular beam epitaxy at temperatures between 400 and 600 °C with a high nominal N concentration (3%). The N content was determined using high resolution x-ray diffraction (HRXRD), secondary ion mass spectrometry (SIMS), and low-temperature photoluminescence (PL). The N concentration determined using these techniques was compared. Additionally, the relationship between the growth temperature and N concentration is discussed. The incorporation of N into interstitial sites resulted in significant variations in the N content as estimated by SIMS, HRXRD, and PL.