Identification and Characterization of the l/f Low-Frequency Noise in GaAs MESFETs Grown on InP Substrates

In this paper we report on low-frequency noise measurements (10Hz to 100kHz) performed on GaAs MESFETs grown on InP substrates as functions of the different biases applied to the drain and gate in the ohmic and saturation regions, in order to identify and characterize the low-frequency noise sources. These measurements show l/f noise spectra over the whole frequency range due to carrier number fluctuations in the channel and related to trapping phenomena. The traps responsible for this noise are located near the channel-buffer interface and the magnitude of the l/f noise for MESFETs with 1 μm buffer-layer thickness is four times higher than for 2 μm thickness.