1/f noise of GaAs Schottky diodes embedded with self-assembled InAs quantum dots

Abstract

Influence of quantum dot growth on the electrical properties of Au/GaAs Schottky diode structures containing self-assembled InAs quantum dots fabricated via atomic layer molecular beam epitaxy is investigated. Current-voltage characteristics and low frequency noise measurements were performed and analyzed. Employing four different structures; containing single quantum dot layer, without quantum dot layer for a reference, thicker capping layer with single quantum dot layer, three quantum dot layers, we find the diode containing single quantum dot layer show largest leakage current and all the dots show 1/f behavior in low frequency noise characteristics. Current dependence of the noise current power spectral density shows that all the dots have linear current dependence at low bias which is explained by the mobility and diffusivity fluctuation. The Hooge parameter was determined to be in the range of 10^-7 to 10^-8. At high bias, the diodes containing quantum dot layer(s) show I_F^β dependence with the value of β larger than 2 (3.9, and 2.7), and the diode without quantum dot layer and thicker capping layer show the value of β smaller than 2 (1.6). The deviation of the values of β from two is explained by the random walk of electrons involving interface states at the metal-semiconductor Schottky barrier interface via barrier height modulation. It seems that the growth of quantum dots induces generation of the interface states with its density increasing towards the conduction band edge. The value of β smaller than 2 means that the interface states density is increasing towards the midgap. Typical value of the interface states density was found to be on the order of 10¹¹ to 10¹²cm²/Vs.