This article describes size dependent charge storage effect of the InAs nanodots in the barrier layers of Al0.5Ga0.5As/GaAs field-effect diodes. This charging effect is analyzed by a capacitance-voltage (C-V) measurement at 77 K, and results in a clockwise hysteresis loop due to the electron storage at nanodot potentials. It is revealed that the number of stored electrons is nearly independent of dot size, and the amount of stored charge increases proportionally with dot density. The retention time of the stored charge, however, is deteriorated dramatically by the inclusion of coalesced dots in the storage nodes. These C-V characteristics are in good agreement with their photoluminescence properties.

This letter describes the memory effect of an AlGaAs/GaAs heterojunction field-effect transistor that contains InAs nanodots in the barrier layer. The device experiences a shift of threshold gate voltage, as a function of the amount of the electrons trapped in the nanodots. These trapped electrons can be injected by applying a positive gate voltage and be erased by a visible light illumination at negative gate bias. Although the shift of the threshold gate voltage volatilizes with the time after the memory programing operation, a considerable part of the shift is retained even after 100 h at room temperature.

Photoluminescence (PL) of quantum dots embedded in high potential barriers is studied as functions of barrier thickness and temperature. With the increase of barrier thickness, both the strengthened two-dimensional electron gas (2DEG) structure and strongly localized electron wave functions can increase the carrier recombination. The optical properties of two different-barrier-thickness samples exhibit different characteristics with the decreased measurement temperatures. The PL recombination characteristic of the samples with the barriers adjacent to a Si-doping GaAs layer is different fromthat of samples with the barrier adjacent to an i-GaAs layer.

This paper describes molecular beam epitaxial growth of high-quality CdTe films in the (100)-orientation on (100)-GaAs substrates. It is revealed by a photoluminescence measurement that a defect-related emission band is dominant when the CdTe film is directly grown on the GaAs substrate. After applying a postgrowth annealing, however, the crystalline quality of the CdTe film is improved to exhibit a reduced defect-related emission band and an intense emission peak from excitons. Although the CdTe surface after annealing is rough due to the formation of thermal etchpits, a MnTe capping prior to the annealing is found to be effective to keep the surface smooth. The usefulness of this method is demonstrated by applying the annealed MnTe/CdTe film as a buffer layer for high-quality CdTe overgrowth.