1063-7397/04/3304- © 2004 MAIK “Nauka /Interperiodica”
Russian Microelectronics, Vol. 33, No. 4, 2004, pp. 236–240. Translated from Mikroelektronika, Vol. 33, No. 4, 2004, pp. 290–295.
Original Russian Text Copyright © 2004 by Egorkin, Morocha, Shmelev, Kapaev, Kazakov.
In acoustic charge-transport devices the carrier den-
sity in charge packets is a nonlinear function of injec-
tion-current amplitude. Acoustoelectric attenuation is
enhanced by interaction between charge packets being
transported and the electric ﬁeld associated with the
acoustic wave. The shielding effect of the electrons
impedes the charge transport.
The shielding was detected in recent experiments on
the modulation of photoluminescence spectra by an
acoustoelectric ﬁeld; it was manifested in the wave
amplitude decreasing with growing laser intensity
It appears that further investigation is needed into
the nonlinear effect of charge density being transported
on the acoustoelectric ﬁeld.
This paper reports an experimental and theoretical
study of a nonlinear transfer characteristic representing
acoustic charge transport in an AlGaAs/GaAs hetero-
Figure 1 is a schematic diagram of the heterostruc-
ture. On a GaAs substrate the following layers are
) 100-Å n
) 200-Å GaAs,
) 400-Å AlGaAs, (
) 700-Å i-GaAs, (
AlGaAs, and (
) 2000-Å GaAs. Layers
a transport channel and a buffer, respectively. The
thicknesses and doping levels of the six layers were set
so as to ensure desired conditions in the channel,
namely, to isolate the channel from external inﬂuence,
to minimize the free-carrier density, and to create a
transverse ﬁeld at which the loss is minimal . The
parameter values were determined by numerical solu-
tion of Poisson’s equation.
The heterostructure was implemented as a chip
including two interdigital transducers and two Schottky
diodes. The transducers generate and detect a surface
Injection-Current Dependence of the Acoustoelectric Signal
in AlGaAs/GaAs Heterostructures
V. I. Egorkin*, A. K. Morocha*, S. S. Shmelev*, V. V. Kapaev**, and I. P. Kazakov**
* Moscow State Institute of Electronic Engineering (Technical University), Moscow, Russia
** Lebedev Physical Institute, Russian Academy of Sciences, Moscow, Russia
Received September 24, 2003
—Acoustic charge transport is studied experimentally and theoretically. To this end, an AlGaAs/GaAs
heterostructure is designed and fabricated with set geometrical and electrical parameters of the layers. Its trans-
fer characteristic is measured, i.e., the variation of output voltage with injection current. The behavior of the
curve is explained within an analytical model. The conclusions are supported by numerical simulation.
AND FABRICATION TECHNOLOGY
Schematic diagram of acoustic charge transport in the AlGaAs/GaAs heterostructure.