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.

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.

An Al0.5Ga0.5As/GaAs heterojunction field-effect transistor which consists of InAs nanodots in the barrier layer and a GaAs quantum well channel is grown by molecular beam epitaxy, and the device performance and the electron transport from the quantum well to the nanodots are studied. These InAs nanodots are grown by self-assembling in a vertically stacked form, and their optical and electrical properties are characterized by photoluminescence and capacitance-voltage measurements. The electrical injection of electrons confined at the nanodots produces a persistent electron trapping which yields a memory function in the device performance, showing a potential application for roomtemperature operation.