Study of low-frequency excess noise in GaN materials

Proceedings of the 8th ICEM 2002, XI'an, 10-14 June 2002We report detailed investigations of low-frequency excess noise in GaN-based metal-semiconductor-metal devices fabricated on GaN thin films deposited by RF-plasma assisted molecular beam epitaxy on different types of buffer structures. Our experimental data indicate two orders of magnitude reduction in flicker noise for samples grown on double buffer layers that consist of a GaN intermediate temperature buffer layer on top of a thin AlN high temperature buffer layer. Experimental results on the temperature dependencies of the current noise power spectra stipulate that the noise arises from thermally activated trapping and detrapping of carriers. Based on the thermal activation model for 1/f noise, we computed the energy distribution of the traps responsible for the observed flicker noise. We also performed systematic studies on the hot-electron degradation of the devices through the application of a large voltage bias. The data demonstrate substantial improvement in the hot-electron hardness for devices fabricated on the double buffer layer structures.Department of Electronic and Information Engineerin