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.

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.

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.