Low frequency drain noise comparison of AlGaN/GaN HEMT's grown on silicon, SiC and sapphire substrates

This work deals with the analysis of low frequency drain noise in gallium nitride FETs on silicon, SiC and sapphire substrates. A comparison of the quality in terms of LF noise of these technologies is established. On the basis of the 1/f normalized noise in linear regime, i.e. the alpha(H)/N parameter, GaN HEMT on sapphire and Si substrates have demonstrated as low LF noise level as GaAs based FET's while HEMTs on SiC present a 1/f noise level which is one order of magnitude higher. The analysis of the normalized drain current spectral density vs. the normalized gate voltage Vgn=(Vg-Vt)/\Vt\ has been studied. In particular, for devices on Si substrate, we have pointed out that the evolution of the 1/f noise level strongly depends on the evolution of the gate leakage current. (C) 2003 Elsevier Ltd. All rights reserved.