Hot-electron noise and diffusion in AlGaAs/GaAs

Abstract

The electric field dependence of the microwave noise temperature and the diffusion coefficient are found to be significantly different for two sets of AIGaAsJGaAs structures with different spacer thickness and aluminium mole fraction. In the samples with a 'wide' quantum well (OW), one maximum of the diffusion coefficient is observed at fields below the threshold for the intervalley intersubband gap wider than the k,T,,. A microscopic explanation of t h e observed noise spectra of AlGaAsiGaAs is given and used to determine kinetic parameters of the heterostructures.

Fluctuations and Ultrafast Processes in Voltage-Biased Two-Dimensional Channels

“…The gating pulse is delayed for measurements of the noise temperature before, during, and after the voltage pulse. This helps to study and minimize channel self-heating 12 squares 16 -AlGaAs/GaAs (33 %Al, 103000 cm 2 /(Vs), 1.9·10 11 cm -2 ); stars 5 n-type GaAs sample (77000 cm 2 /(Vs), 9·10 14 cm -3 ). Curves guide the eye.…”

“…The RST noise causes local maxima of the spectral intensity at 1 2 / n n ~ 1 (Fig. 2, pentagons and squares) 15,16 . The position of the maximum depends on the Al mole ratio in the AlGaAs layer: the fluctuations appear at a higher field if the conduction band offset at the interface is higher.…”

“…The maximum height and Eq. (1) are used for estimation of the RST relaxation time constant 16,17 : RST τ ~ 5 ps and ~ 10 ps. Suppression of RST noise in short 2DEG channels suggests an independent way for estimation of the RST relaxation time constant 17 .…”

Ultrafast two-dimensional electron gas detector and mixer for terahertz radiation

“…This value is close to values measured in similar 2DEG samples. 12 The 2DEG medium thus has a great advantage compared with typical superconductors ͓D for Nb ͑Ref. 4͒ is about 1 cm 2 /s͔.…”

“…The value of m for 2DEG driven by THz radiation appears to be different from that found in equilibrium conditions, or when the 2DEG is driven by a dc field. 10,[12][13][14][15] A likely value of the frequency cci ϭ1/ m , at which charge-carrier inertia becomes important, is a few hundred GHz. Close to this frequency, one can approximate the effect of the charge-carrier inertia on the equivalent circuit of the device by adding an inductance in series with the device resistance.…”