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12 May 2003 Low-frequency drain noise in AlGaN/GaN HEMTs on Si substrate
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Proceedings Volume 5113, Noise in Devices and Circuits; (2003)
Event: SPIE's First International Symposium on Fluctuations and Noise, 2003, Santa Fe, New Mexico, United States
The low frequency noise level is one of the key parameters, which determines the device potential for microwave applications. The fabrication of AlGaN/GaN HEMT on Si produces much more dislocations than on sapphire or SiC substrates. Therefore, it is important to analyse the influence of traps on the LF noise level of such devices. Devices under test are undoped AlGaN/GaN HEMT on silicon substrate. These non-passivated devices present gate geometries of 3.5μm by (2x75)μm and 1.5μm by (2x50)μm. At 300K, output characteristics Id-Vds present kink effect occurring at Vds around 6V and high values of Vgs. As this effect vanishes for temperature above 300K, deep traps are activated. LF drain noise measurements were performed in the ohmic regime. We have measured the low frequency drain noise spectral density :- for drain current of 2mA with Vgs varying from -2V to 0V, - for Vgs of 0V and -1V with Id from 2 to 6 mA. The dispersion of the drain noise level is about one order of magnitude difference. A typical spectrum is composed of 1/f noise which level is in the range of the ones measured on AlGaAs/GaAs HEMT and several generation-recombination components. Cut-off frequencies of G-R noise are typically lower than 100Hz. Therefore, the 1/f noise is screened by G-R noise at low frequencies and becomes preeminent for frequencies higher than 500Hz. The 1/f noise level verifies the Hooge relation. It is proportional to the square of Id. We have found that the αH/N parameter (that is the normalized drain current spectral density fSid/Id²) is in the range of 3×10-11 to 3×10-10.
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Nathalie Malbert, Nathalie Labat, Arnaud Curutchet, Andre Touboul, Christophe Gaquiere, and Auxens Minko "Low-frequency drain noise in AlGaN/GaN HEMTs on Si substrate", Proc. SPIE 5113, Noise in Devices and Circuits, (12 May 2003);

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