Electron transport in crossed electric and magnetic fields under the condition of the electron streaming in GaN
High-field electron transport has been studied in crossed electric and magnetic fields in bulk GaN with doping of 10¹⁶ cm⁻³ and compensation around 90% at the low lattice temperature (30 K). The electron distribution function, the field dependences of the ohmic and Hall components of the drift veloc...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2015
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| Цитувати: | Electron transport in crossed electric and magnetic fields under the condition of the electron streaming in GaN / G.I. Syngayivska, V.V. Korotyeyev // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2015. — Т. 18, № 1. — С. 79-85. — Бібліогр.: 28 назв. — англ. |
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irk-123456789-1207292017-06-13T03:06:38Z Electron transport in crossed electric and magnetic fields under the condition of the electron streaming in GaN Syngayivska, G.I. Korotyeyev, V.V. High-field electron transport has been studied in crossed electric and magnetic fields in bulk GaN with doping of 10¹⁶ cm⁻³ and compensation around 90% at the low lattice temperature (30 K). The electron distribution function, the field dependences of the ohmic and Hall components of the drift velocity have been calculated using the Monte Carlo method in the wide range of applied electric (3…15 kV/cm) and magnetic (1…10 T) fields. Two external electrical circuits with short- and open-circuited Hall contacts have been analyzed. For a sample with short-circuited Hall contacts, there are the ranges of magnetic and electric fields where the non-equilibrium electron distribution function has a complicated topological structure in the momentum space with a tendency to formation of the inversion population. For these samples, field dependences of the ohmic and Hall components of the drift velocity have specific character. The ohmic component has the inflection point that corresponds to the maximum point of the Hall component. For the sample with open-circuited Hall contacts, field dependences of the drift velocity demonstrate a sub-linear growth without any critical points. It has been shown that there are ranges of the applied electric and magnetic fields for which the drift velocity exceeds zero magnetic field values 2015 Article Electron transport in crossed electric and magnetic fields under the condition of the electron streaming in GaN / G.I. Syngayivska, V.V. Korotyeyev // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2015. — Т. 18, № 1. — С. 79-85. — Бібліогр.: 28 назв. — англ. 1560-8034 DOI: 10.15407/spqeo18.01.079 PACS 72.20.Ht, 72.20.Dp, 73.23.-b, 85.35.-p http://dspace.nbuv.gov.ua/handle/123456789/120729 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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High-field electron transport has been studied in crossed electric and magnetic fields in bulk GaN with doping of 10¹⁶ cm⁻³ and compensation around 90% at the low lattice temperature (30 K). The electron distribution function, the field dependences of the ohmic and Hall components of the drift velocity have been calculated using the Monte Carlo method in the wide range of applied electric (3…15 kV/cm) and magnetic (1…10 T) fields. Two external electrical circuits with short- and open-circuited Hall contacts have been analyzed. For a sample with short-circuited Hall contacts, there are the ranges of magnetic and electric fields where the non-equilibrium electron distribution function has a complicated topological structure in the momentum space with a tendency to formation of the inversion population. For these samples, field dependences of the ohmic and Hall components of the drift velocity have specific character. The ohmic component has the inflection point that corresponds to the maximum point of the Hall component. For the sample with open-circuited Hall contacts, field dependences of the drift velocity demonstrate a sub-linear growth without any critical points. It has been shown that there are ranges of the applied electric and magnetic fields for which the drift velocity exceeds zero magnetic field values |
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Syngayivska, G.I. Korotyeyev, V.V. |
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Syngayivska, G.I. Korotyeyev, V.V. Electron transport in crossed electric and magnetic fields under the condition of the electron streaming in GaN Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Syngayivska, G.I. Korotyeyev, V.V. |
| author_sort |
Syngayivska, G.I. |
| title |
Electron transport in crossed electric and magnetic fields under the condition of the electron streaming in GaN |
| title_short |
Electron transport in crossed electric and magnetic fields under the condition of the electron streaming in GaN |
| title_full |
Electron transport in crossed electric and magnetic fields under the condition of the electron streaming in GaN |
| title_fullStr |
Electron transport in crossed electric and magnetic fields under the condition of the electron streaming in GaN |
| title_full_unstemmed |
Electron transport in crossed electric and magnetic fields under the condition of the electron streaming in GaN |
| title_sort |
electron transport in crossed electric and magnetic fields under the condition of the electron streaming in gan |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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2015 |
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http://dspace.nbuv.gov.ua/handle/123456789/120729 |
| citation_txt |
Electron transport in crossed electric and magnetic fields under the condition of the electron streaming in GaN / G.I. Syngayivska, V.V. Korotyeyev // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2015. — Т. 18, № 1. — С. 79-85. — Бібліогр.: 28 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
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AT syngayivskagi electrontransportincrossedelectricandmagneticfieldsundertheconditionoftheelectronstreamingingan AT korotyeyevvv electrontransportincrossedelectricandmagneticfieldsundertheconditionoftheelectronstreamingingan |
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2025-07-08T18:28:48Z |
| last_indexed |
2025-07-08T18:28:48Z |
| _version_ |
1837104448625704960 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2015. V. 18, N 1. P. 79-85.
doi: 10.15407/ spqeo18.01.079
© 2015, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
79
PACS 72.20.Ht, 72.20.Dp, 73.23.-b, 85.35.-p
Electron transport in crossed electric and magnetic fields
under the condition of the electron streaming in GaN
G.I. Syngayivska and V.V. Korotyeyev
V. Lashkaryov Institute of Semiconductor Physics, Department of Theoretical Physics, NAS of Ukraine
41, prospect Nauky, 03028 Kyiv, Ukraine; e-mail: singg@ukr.net; koroteev@ukr.net
Abstract. High-field electron transport has been studied in crossed electric and magnetic
fields in bulk GaN with doping of 10
16
cm
–3
and compensation around 90% at the low
lattice temperature (30 K). The electron distribution function, the field dependences of
the ohmic and Hall components of the drift velocity have been calculated using the
Monte Carlo method in the wide range of applied electric (3…15 kV/cm) and magnetic
(1…10 T) fields. Two external electrical circuits with short- and open-circuited Hall
contacts have been analyzed. For a sample with short-circuited Hall contacts, there are
the ranges of magnetic and electric fields where the non-equilibrium electron distribution
function has a complicated topological structure in the momentum space with a tendency
to formation of the inversion population. For these samples, field dependences of the
ohmic and Hall components of the drift velocity have specific character. The ohmic
component has the inflection point that corresponds to the maximum point of the Hall
component. For the sample with open-circuited Hall contacts, field dependences of the
drift velocity demonstrate a sub-linear growth without any critical points. It has been
shown that there are ranges of the applied electric and magnetic fields for which the drift
velocity exceeds zero magnetic field values.
Keywords: Monte Carlo method, gallium nitride, magneto-transport.
Manuscript received 07.10.14; revised version received 04.12.14; accepted for
publication 19.02.15; published online 26.02.15.
1. Introduction
Semiconductor compounds of group-III nitrides, in
particularly GaN, InN and AlN, are perspective
materials for the modern high-power and high-frequency
micro- and optoelectronics. The strong electron-optical-
phonon coupling, large optical phonon energy,
sufficiently high electron mobility are inherent for these
materials [1-3]. In the literature, nitride materials are
widely discussed as candidates for development of the
electrical pumping THz sources, particularly, based on
the Gunn effect (under ultra-strong applied electric fields
≈100 kV/cm) [4-7] as well as streaming transport regime
and the optical-phonon transit-time resonance (OPTTR)
(under moderate applied electric fields ≈2…10 kV/cm)
[8-12]. The streaming transport regime is associated with
formation of the strongly-anisotropic distribution
function under the sufficiently strong applied electric
field. In this case, a dynamic negative differential
conductivity can be realized in the specific frequency
ranges. Recently, we investigated conditions of
streaming and OPTTR effects in the case of
compensated GaN, where an undesirable influence of the
non-elastic ee scattering [10] can be avoided. We
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2015. V. 18, N 1. P. 79-85.
doi: 10.15407/ spqeo18.01.079
© 2015, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
80
specified intervals of applied electric fields E
(3…10 kV/cm), ambient temperatures T (30…150 K)
and frequency ranges (0.2…2 THz), where streaming
and OPTTR effects can occur [13, 14]. Also, we
investigated high-frequency properties of the
compensated GaN under streaming conditions in the
case of applied parallel magnetic field ( EH | | ) [15, 16]
and found that this field has no effect on steady-state
characteristics but essentially changes the frequency
spectra of dynamic mobility tensor.
The presence of the external magnetic field, H,
transversal to the direction of the electric field, E , can
essentially change dynamics of hot electrons [17] and
can effect on the form of the distribution function and
current-voltage characteristics. Depending on the ratio of
the amplitudes E and H, three different transport regimes
can be realized. In the weak magnetic fields such as
0
*
1< PcEmHH (where 0
*
0 2= mP is the
electron momentum corresponding to the optical phonon
energy 0 , m
*
– electron effective mass, and c – light
velocity) electron trajectories in the momentum space
are slightly curved, the streaming cyclic motion is
maintained, and the electron distribution function
remains strongly anisotropic in the direction of the
electric field. For intermediate magnetic fields, when
121 2<< HHHH , the two electron groups can exists.
Electrons of the first group interact with optical phonons
and execute the streaming cyclic motion. Electrons of
the second group do not interact with optical phonons
and move along closed circular orbits in the passive
region of the momentum space ( 0|<| PP
). The average
energy of electrons belonging to the second group can
essentially exceed the thermal energy, 3/2×kBT (kB is the
Boltzmann constant). Therefore, at a sufficiently high
electron concentration in the second group the inverted
electron distribution can arise, i.e. the distribution
function with a double-humped shape in the energy
space is formed. In the case of strong magnetic fields,
such as H > H2, trajectories of the most electrons are
completely located in the passive region, and the optical
phonon emission is strongly suppressed. In this case, the
electron distribution function in the momentum space is
almost isotropic, and there occurs a collapse of the
ohmic current.
The study of the hot electron transport in crossed
electric and magnetic fields attracts much attention
because of a perspective to obtain inverted distributions
necessary for high-frequency generators. However, in
conventional A
III
B
V
semiconductor compounds n-GaAs,
n-InSb, n-InP these distributions cannot be formed [18-
20]. The aim of the paper is to study the hot-electron
transport in crossed electric and magnetic fields in the
novel semiconductor material GaN, in particularly, we
consider the effect of magnetic field on the electron
distribution function and analyze current-voltage and
induction-current characteristics for cases of short-
circuited and open-circuited Hall contacts.
2. Transport model
We consider the compensated bulk GaN of cubic
modification [21] at the low lattice temperature of T =
30 K with impurity and electron concentrations of Ni =
316 cm10 and Ne = 315cm10 , respectively. The electron
dispersion law is assumed to be parabolic. To calculate
electron transport characteristics, the single-particle
algorithm of the Monte Carlo procedure [14, 22-24] was
applied. In simulation, we assume the electron effective
mass, emm 0.2=* (where em is the free electron mass)
and the optical phonon energy meV92=0 [25] and
take into account the main three scattering mechanisms:
scattering by ionized impurities, acoustic phonons and
polar optical phonons. We assume that electric field is
applied along the x-axis (the direction of the ohmic
current) and the magnetic field is applied along the z-
axis. The y-axis is the direction of the Hall current (or
field). It should be noted that in all the calculations the
magnetic field is treated as a classical field. An
estimation shows that for hot electrons with the averaged
energies 30…50 meV gained within the range of
electric fields 3 to 10 kV/cm the inequality <<c is
fulfilled even at magnetic fields of the order of 10 T.
Here, cmeHc
*= is the cyclotron frequency with the
elementary charge, e.
We concentrate to the regions of the magnitudes of
E and H, where three different transport regimes can be
realized (see the diagram in Fig. 1).
In the region (I), the streaming regime is still
survived and all electrons reach the energy of the optical
phonon. The region (II) corresponds to the case when a
portion of electrons has trajectories closed in the passive
region. In the region (III), almost all electron trajectories
are closed in the passive region. For example, for the
electric field E = 5 kV/cm, the region (I) corresponds to
magnetic fields H < 1.25 T, region (II) – 1.25 T <
H < 2.5 T and region (III) – H > 2.5 T.
Fig. 1. The E–H plane. Straight lines 1 and 2 correspond to the
functions cmHPE
0= and cmHPE 2= 0 .
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2015. V. 18, N 1. P. 79-85.
doi: 10.15407/ spqeo18.01.079
© 2015, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
81
3. Electron distribution function
The discussion of the non-equilibrium distribution
function is carried out in the energy, f , and
momentum, yx PPf , , spaces for the spatially-unlimited
sample. Fig. 2a demonstrates evolution of f , with
variation of the magnetic field at the given electric field
E = 5 kV/cm. As seen, in the case of the weak magnetic
fields T1H the streaming distribution is slightly
modified: the curve 1 is close to the dash-dotted curve.
Note, at this electric field the values of magnetic fields
up to 1.2 T correspond to the region (I) in the diagram
(see Fig. 1). In the opposite case of strong magnetic
fields corresponding to the region (III), for example at
H = 5.7 T, most of electrons move along the trajectories
closed in the passive region, and they do not interact
with optical phonons. As a result, the distribution
function f is almost localized in the passive region.
Fig. 2. Panel (a): The electron distribution function )(f for
different magnetic fields. Curves 1, 2, 3 correspond to H = 1,
2.3, 5.7 T, respectively (these fields are marked by points in
Fig. 1). The dash-dotted curve is obtained at H = 0. Panel (b):
The contour plot of the electron distribution function
yx PPf , at H = 2.3 T. The dashed circle shows the
conditional boundary between passive and active regions. The
sign × denotes the maximum of the distribution. E = 5 kV/cm.
For intermediate magnetic fields corresponding to
the region (II), for example H = 2.3 T, it is observed a
distinctive reconstruction of the form of distribution
function in the energy space. The effect of accumulation
of high-energy electrons in the energy interval
0.9][0.5/ 0 is clear seen. In the momentum
space, the distribution function, yx PPf , , acquires the
complicated topological structure (Fig. 2b) because of
the coexistence of two groups of carriers: electrons
executing streaming motion and electrons moving along
cyclotron orbits. The maximum of yx PPf , is
essentially shifted along both ohmic and Hall directions.
In the works [20, 26] for GaAs, it was shown that
under weak scattering in the passive region, so that
5.02 c (where τ is the scattering time in the
passive region) it can be formed a double-humped
distribution function f . In our case of GaN with the
impurity concentration of 316 cm10 at H = 2.3 T an
estimation gives ps5.0 and 18.02 c . As a
result, we observe only weak tendency to formation of
this distribution.
In the model case of the very low impurity
concentration (Ni < 314 cm10 ), scattering in the passive
region is limited by acoustic phonons for which
ps50 and for magnetic fields corresponding the
region (II), for example for H = 2 T, 182 c . As a
result, it is observed a well-pronounced separation of
the distribution function by two parts. The spindle-
shaped part corresponds to electrons trapped in the
passive region, and the streaming-like part corresponds
to electrons interacting with optical phonons (see
Fig. 3b). In this case, the distribution function in the
energy space has a double-humped shape with an
inversion population near the boundary of the passive
and active regions (see Fig. 3a).
Thus, in bulk-like GaN samples with Ni =
316 cm10 and Ne = 315cm10 at T = 30 K, the
distribution function with inversion is not formed due to
the intensive scattering in the passive region. This
distribution can be obtained only in the limit of the small
impurity concentration, Ni
314cm10 .
4. Transport characteristics
The transport characteristics in the magnetic field
depend on the choice of configuration of the external
electrical circuit. There are two typical schemes of
measurements: 1) scheme of short-circuited Hall
contacts and 2) scheme of open-circuited Hall contacts.
The first scheme also can be realized for the short
sample in the direction of the electric field, and the
second scheme can be realized for the long sample in the
direction of the electric field. Calculations of transport
characteristics were carried out for both schemes.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2015. V. 18, N 1. P. 79-85.
doi: 10.15407/ spqeo18.01.079
© 2015, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
82
Fig. 3. Panel (a): The electron distribution in the energy space.
Panel (b): The contour plot of the electron distribution function
yx PPf , in the momentum space. For both panels, E =
5 kV/cm and H = 2 T.
4.1. Short-circuited Hall contacts
For the case of short-circuited Hall contacts, the effect of
the charge accumulation at Hall edges can be neglected,
and the Hall field, Eh, is equal to zero. In the magnetic
field, the Lorentz force deviates electrons to the y-
direction, which results in appearance of the Hall
component of the drift velocity, Vh, transversal to the
applied electric field E. Thus, the vector of the drift
velocity totV
subtends an angle θ (the Hall angle) with
the vector of the applied electric field E
. The angle θ
can be determined as follows: dh VV=tan , where Vd is
the ohmic component of the drift velocity, which is
directed along E
. The Monte Carlo procedure allows to
calculate the components Vh and Vd and angle θ.
Typical magnetic and electric fields dependences of
both ohmic and Hall components of the drift velocity are
shown in Figs. 4a and 4b, respectively.
As seen, functions HVd and HVh consist of
three portions with a distinct behavior. Let us consider
the pair of curves calculated for 5 kV/cm. In magnetic
fields up to ≈1 T, HVd is weakly changed, and HVh
exhibits a linear behavior. Starting from the field 1.25 T,
when accumulation of electrons in the passive region is
activated, HVd is rapidly decreased with increasing the
magnetic field. The inflection point in the dependence of
HVd corresponds to the maximum point in the
dependence of HVh . In magnetic fields H > 2.5 T (the
characteristic field H2), both characteristics show a
gradually decreasing behavior. In the range of high
magnetic fields H > 5 T, the electron drift is almost
suppressed along E (the collapse of the ohmic current)
but it is still remained along the Hall direction. With
increasing the applied electric field, both characteristic
magnetic fields H1 and H2 are increased, too, therefore it
is observed the general broadening of magnetic field
dependences with shifting the inflection and maximum
points to the range of stronger magnetic fields (see thin
lines in Fig. 4a).
Fig. 4. Panel (a): Dependences of HVd (solid lines) and
HVh (dashed lines) at E = 5 kV/cm (thick lines) and E =
10 kV/cm (thin lines). Points depict characteristic magnetic
fields H1 = 1.14 T and H2 = 2.3 T. Panel (b): Dependences of
EVd (solid lines) and EVh (dashed lines) at H = 2.3 T
(thick lines) and H = 4.6 T (thin lines). Points mark
characteristic electric fields E = 4.6, 9.2 kV/cm, corresponding
to magnetic fields H1 and H2. The velocity V0 = 4∙107 cm/s.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2015. V. 18, N 1. P. 79-85.
doi: 10.15407/ spqeo18.01.079
© 2015, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
83
Fig. 5. Panel (a): Field dependences of the drift velocity at H =
3.4 and 5.7 T (curves 1 and 2, respectively). The dash-dotted
curve is calculated for H = 0. Panel (b): Dependences of
dh EE for the magnetic fields H = 1.14, 2.3, 3.4, 4.6 T
(curves 1, 2, 3 and 4, respectively). The dashed straight line
crosses curves 1–4 at points where Eh is equal to Ed .
Electric field characteristics Vd (E) and Vh (E) also
have three specific intervals. At H = 2.3 T (see thick
lines in Fig. 4b), a super-linear growth of EVd and
linear growth of Vh (E) are observed in the interval
0…5 kV/cm that corresponds to the region (III) in the
diagram (Fig. 1). The inflection point in the dependence
of Vd (E) corresponds to the maximum point in the
dependence of Vh (E). In the range of electric fields
corresponding to the region (II), the ohmic component
shows a sub-linear behavior with tending to the quasi-
saturation at higher electric fields belonging to the
region (I). In this case, the Hall component is essentially
decreased within the range E = 5…9 kV/cm. At E >
10 kV/cm, it is observed a slow dropping behavior of
EVh . With increasing the applied magnetic field, the
inflection and maximum points are shifted to the range
of stronger electric fields.
It should be noted that dependences of Vd and Vh
have the crossing point (at which the Hall angle is equal
to 4 ). Thus, there are ranges of E and H where one of
drift velocity components dominates.
4.2. Open-circuited Hall contacts
For the case of the sample with open-circuited Hall
contacts (an open-circuited sample), the Hall electric
field, Eh, is not equal to zero due to the charge
accumulation on Hall edges, and the Hall current is
absent. For this external circuit, it is usually measured a
total current flowing through the sample, and the Hall
voltage as functions of the applied field Ed. If the sample
is so long in the Hall direction that spatial
inhomogeneity of the electric field near the Hall contacts
can be neglected, then field dependences of the drift
velocity, dtot EV , and Hall field, dh EE , can be easy
obtained using results for the case of a sample with
short-circuited Hall contacts (a short-circuited sample).
From simple geometrical considerations, it follows:
22= hdtot VVV , cos= EEd , sin= EEh . For the
open-circuited sample, dependences of dtot EV
(Fig. 5a) have monotonic behavior, and in contrast to the
short-circuited sample, there are no inflection points.
Note that the drift velocity under applied magnetic fields
can exceed its value at zero magnetic field. The similar
result was obtained and discussed in refs. [27, 28]
relating to n-GaAs and n-InP samples.
Fig. 5b demonstrates dependences of dh EE for
several values of magnetic fields. All dependences have
similar behavior: in electric and magnetic fields
corresponding to the region (III), the Hall field exhibits
rapid growth to the maximum. Then, for the applied
fields corresponding to the region (II) the Hall field
smoothly decreases and remains almost constant at
applied fields belonging to the region (I).
5. Conclusions
The high-field electron transport characteristics in
crossed electric and magnetic fields are studied for the
case of the compensated bulk-like GaN. In the frames of
numerical solution of Boltzmann transport equation by
using the Monte Carlo method, it has been calculated
distribution functions in the energy and momentum
spaces, electric and magnetic field dependences of the
ohmic and Hall components of the drift velocity.
It has been analyzed two cases of the external Hall
circuit. The first one is the case of the sample with short-
circuited Hall contacts, and the second one is the case of
the sample with open-circuited Hall contacts.
For the short-circuited sample, we determined
intervals of applied electric and magnetic fields that
correspond to different regimes of the electron transport.
It has been found that in weak magnetic fields H < H1,
for example in H < 1 T at E = 5 kV/cm, the streaming
transport regime is kept. In this case, the ohmic
component of the drift velocity is weakly, and the Hall
component shows a linear behavior. In the range of the
magnetic fields H1 < H < H2 = 2H1, for example in H =
1…3 T at E = 5 kV/cm, the streaming regime is
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2015. V. 18, N 1. P. 79-85.
doi: 10.15407/ spqeo18.01.079
© 2015, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
84
destroyed, and the distribution function acquires the
complicated topological structure conditioned by the
coexistence of two groups of electrons: electrons of the
first group execute the cyclic motion typical for the
streaming, and electrons of the second group execute the
cyclotron motion without interaction with optical
phonons. In this range of magnetic fields, it is observed
rapid decreasing the ohmic component, and the
characteristic inflection point; the Hall component is
increased and reaches the maximum. The position of
inflection and maximum points correspond to the
magnetic field 2HH ( T5.2H for E = 5 kV/cm).
In the magnetic fields T5H , almost all electrons
execute the cyclotron motion and do not interact with
optical phonons. As a result, the Hall current is
essentially larger than the ohmic one. With increasing
the applied electric field, the style of H-dependences for
both components of the drift velocity is kept, but it is
observed the broadening of dependences (inflection and
maximum points correspond to larger magnetic fields).
The ohmic component of the drift velocity vs E is
the rising characteristic in contrast to its dropping
dependence vs H. Styles of E- and H-dependences of the
Hall component are similar. E-dependences of the drift
velocity also contain inflection (for the ohmic
component) and maximum (for the Hall component)
points. With increasing the applied magnetic field, E-
dependences are changed in the similar way to those of
H-dependences.
For the open-circuited sample, the drift velocity has
only the ohmic component, but the electric field has two
non-zero ohmic and Hall components. The drift velocity
as a function of the applied electric field is the rising
characteristic, and it does not show the peculiarities
inherent for the short-circuited sample (the inflection
point is absent). But at the given magnetic fields, there is
the interval of negative magnetoresistance, i.e. the values
of the drift velocity exceed those in zero magnetic field.
It has been demonstrated that in the presence of the
magnetic field the current-voltage characteristics in the
ohmic direction obtained for samples with short- and
open-circuited Hall contacts are dramatically differed.
References
1. M.J. Manfra, N.G. Weimann, J.W.P. Hsu et al.,
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