Effects Of Natural Ageing In 1/F Noise And Current-Voltage Characteristics Of Submicron Planar MESFETs.

A family of current-voltage (I-V) characteristics and 1/f voltage (source - drain) noise spectra of prototypes of submicron planar GaAs FETs with Schottky flat gate was investigated in linear region. The model of I-V characteristic was suggested. FET channel was described by Shockley model; the crowding of current in passive regions was taken into account as well. Analysis of measured set of I-V characteristics allowed us to define geometrical and electrical parameters of devices more precisely. Effects of natural ageing were found from the measurements made after manufacturing of prototypes (in 2002), and three years later (in 2005). Suggestion on the presence of excess defects in a structure which, as seemed, are presented by dipoles (donor-acceptor pairs) was made; their concentration was estimated and essential decrease of this concentration with the course of time was detected. In order to analyze the 1/f noise the hypothesis of existence of bistable point defects was used. It was supposed that these defects result in specific resistance fluctuations of conducting regions. It was shown that defects from the channel made the main contribution to the 1/f noise; concentration of these defects also was decreased. Experimental data obtained allow us to suppose that the observed 1/f noise is caused by dipoles revealed from analysis of I-V characteristics of FETs. Our results support the δμ model for 1/f noise in GaAs devices. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]