Low-noise behavior of InGaAs quantum-well-structured modulation-doped FET's from 10^-2to 10⁸Hz

Abstract

Equivalent gate noise voltage spectra of 1-µm gate-length modulation-doped FET's with pseudomorphic InGaAs quantum-well structure have been measured for the frequency range of 0.01 Hz to 100 MHz and compared with the noise spectra of conventional AlGaAs/ GaAs MODFET's and GaAs MESFET's. The prominent generation-recombination (g-r) noise bulge commonly observed in the vicinity of 10 kHz in conventional MODFET's at 300 K does not appear in the case of the new InGaAs quantum-well MODFET. Instead, its noise spectra indicate the presence of low-intensity multiple g-r noise components superimposed on a reduced <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/f</tex> noise. The LF noise intensity in the new device appears to be the lowest among those we have observed in any MODFET or MESFET. The noise spectra at 82 K in the new device represent nearly true <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/f</tex> noise. This unusual low-noise behavior of the new structure suggests the effectiveness of electron confinement in the quantum well that significantly reduces electron trapping in the n-AlGaAs, and thus eliminates the g-r noise bulge observed in conventional MODFET's.