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Russian Microelectronics, Vol. 32, No. 6, 2003, pp. 385–390. Translated from Mikroelektronika, Vol. 32, No. 6, 2003, pp. 474–480.
Original Russian Text Copyright © 2003 by Kozlov, Reveleva, Tikhonov.
Recently, the negative relative magnetic-ﬁeld sensi-
tivity of collector current has been found to arise in the
dual-collector lateral bipolar magnetotransistor built
around a diffused well, with the substrate and the well
interconnected externally [1, 2]. The mechanism of the
phenomenon has yet to be understood. Today it is
hardly possible to measure the transport and recombi-
nation of carriers in the device, so we have to rely on
In this study, we explored how the densities and
recombination rates of electrons and holes are distrib-
uted over a diffusion-doped dual-collector lateral npn
magnetotransistor fabricated from a p-well in an n-sub-
strate, with the substrate and the well interconnected
externally. The problem was addressed by computer
simulation for realistic conditions, using a software
package from ISE AG.
The conﬁguration of the transistor is as follows. In
the center of the device, there is an n
region; this is bordered on both sides by two p-regions,
which provide ohmic contact with the base (p-well).
Next to the p-regions there are two n
Ohmic contact with the substrate is by two n
outside the well. Each diffusion-doped region extends
m in the direction perpendicular to the cross section
shown in Figs. 2, 4, 5, and 6. The lateral dimensions and
the thicknesses of the regions can be inferred from the
The collectors were assumed to be biased at 1.5 V,
while the emitter bias was taken to be zero. The applied
magnetic ﬂux density
was set to 1 T and was assumed
to be aligned with the emitter, pointing to the cross sec-
Figure 1 shows how the currents through the elec-
trodes vary with the base–emitter voltage
governs the injection from the emitter. It is seen that
affects the relation between the respective currents
through the two collectors . Speciﬁcally,
is small enough; as
becomes positive. This behavior implies that
the relative sensitivity
changes its sign with growing base current.
< 0.75 V, the emitter current
vary exponentially with
is 800. The exponential variation
indicates that the base current is determined by the
emitter-junction resistance; when the current is low, the
resistance is greater than that of the region between the
base contact and the emitter.
Also note that (i) the emitter current is almost equal
to the substrate current
and (ii) the two collector cur-
rents are very low. These ﬁndings imply that almost all
electrons injected from the emitter are transported into
the substrate, a modest proportion being extracted
through the collectors.
Physically, the above behavior of currents might be
explained as follows. Electrons injected from the emit-
ter travel 4
m before reaching the substrate. In the
well, doping concentration decreases with increasing
distance from the substrate, so that hole density falls
from a maximum to zero when passing from the surface
to the well–substrate junction. Thus, carrier recombina-
tion rate is maximum near the emitter and decreases
when approaching the junction, with recombination
assumed to follow the Shockley–Read–Hall model.
Moreover, there is a drift component of electron current
in the well owing to a nonuniform doping concentration
and the built-in ﬁeld of the well–substrate junction. In
the substrate, electrons are majority carriers and elec-
tron current is due to carrier relaxation.
Dual-Collector Lateral Bipolar Magnetotransistor:
Carrier Transport and Relative Sensitivity
A. V. Kozlov*, M. A. Reveleva*, and R. D. Tikhonov**
* Moscow State Institute of Electronic Engineering (Technical University), Moscow, Russia
** Technological Centre, Moscow State Institute of Electronic Engineering (Technical University), Moscow, Russia
Received April 2, 2003
—A computer simulation is presented of the carrier transport in a diffusion-doped dual-collector lat-
eral bipolar magnetotransistor fabricated from a p-well in an n-substrate, with the substrate and the well inter-
connected externally. The mechanism by which the negative relative sensitivity of collector current arises is
addressed. Carrier transport under low-level injection is analyzed. It is concluded that negative relative sensi-
tivity results from the magnetic-ﬁeld-induced redistribution of electrons and holes that recombine in the base.
This model of negative relative sensitivity might be called the
bulk recombination mechanism.
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