Low frequency noise of GaAs Schottky diodes with embedded InAs quantum layer and self-assembled quantum dots

The electrical properties of InAs quantum layer (QL) and self-assembled quantum-dots (QDs), embedded in GaAs, are investigated by low-frequency noise measurements using Au/n-GaAs Schottky diodes as test devices. The measurements are carried out in the forward conduction regime with forward current IF as a parameter. Current–voltage and capacitance–voltage measurements indicate that GaAs and GaAs/InAs-QL Schottky diodes are nearly ideal, even though defects are present in the space–charge region of GaAs/InAs-QD Schottky diodes. In GaAs and GaAs/InAs-QL Schottky diodes, the power spectral density of the current fluctuations, S1, shows 1/f behavior and is proportional to IF2, which is explained by modulation of the barrier height due to trapping and detrapping phenomena. In GaAs/InAs-QD Schottky diodes, S1 shows 1/fγ (with γ≈0.6) behavior and is proportional to IF2 in the low current region and proportional to IF2.5 in the high current region. These noise data are explained by the generation of band tail states with exponential energy distribution in the GaAs layers due to QD formation.