Characteristics of 1/f noise in Au/GaAs Schottky diode embedded with self-assembled InAs quantum dots

Abstract

The 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 a single quantum-dot layer, without quantum-dot layer for reference, thicker capping layer with a single quantum-dot layer, and three quantum-dot layers, we find that the diode containing a single quantum-dot layer shows the 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(beta) dependence with a value of 0 larger than 2 (3.9, and 2.7), and the diode without quantum-dot layer and thicker capping layer shows a value of beta smaller than 2 (1.6). The deviation of the values of beta 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 density increasing towards the conduction-band edge. The value of smaller than 2 means that the interface-state density increases towards the midgap. A typical value of the interface-state density was found to be on the order of 10(11) to 10(12) cm(2)/Vs.