HIGH-FIELD ELECTRON TRANSPORT CONTROLLED BY OPTICAL PHONON EMISSION IN NITRIDES

We have investigated the problem of electron runaway at strong electric fields in polar semiconductors focusing on the nanoscale nitride-based heterostructures. A transport model which takes into account the main features of electrons injected in short devices under high electric fields is developed. The electron distribution as a function of the electron momenta and coordinate is analyzed. We have determined the critical field for the runaway regime and investigated this regime in detail. The electron velocity distribution over the device is studied at different fields. We have applied the model to the group-III nitrides: InN, GaN and AlN. For these materials, the basic parameters and characteristics of the high-field electron transport are obtained. We have found that the transport in the nitrides is always dissipative. However, in the runaway regime, energies and velocities of electrons increase with distance which results in average velocities higher than the peak velocity in bulk-like samples. We demonstrated that the runaway electrons are characterized by the extreme distribution function with the population inversion. A three-terminal heterostructure where the runaway effect can be detected and measured is proposed. We also have considered briefly different nitride-based small-feature-size devices where this effect can have an impact on the device performance.

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TEMPERATURE DEPENDENCE OF HIGH FIELD ELECTRON TRANSPORT PROPERTIES IN WURTZITE PHASE GaN FOR DEVICE MODELING

International Journal of Modern Physics B ◽

10.1142/s0217979208048620 ◽

2008 ◽

Vol 22 (22) ◽

pp. 3915-3922 ◽

Cited By ~ 1

Author(s):

A. R. BINESH ◽

H. ARABSHAHI ◽

G. R. EBRAHIMI ◽

M. REZAEE ROKN-ABADI

Keyword(s):

Electron Transport ◽

Electric Fields ◽

Dominant Role ◽

Electron Velocity ◽

Differential Conductance ◽

Device Modeling ◽

Wurtzite Phase ◽

Ensemble Monte Carlo ◽

Electron Transport Properties ◽

High Electric Fields

An ensemble Monte Carlo simulation has been used to model bulk electron transport at room and higher temperatures as a function of high electric fields. Electronic states within the conduction band valleys at the Γ1, U, M, Γ3 and K are represented by non-parabolic ellipsoidal valleys centred on important symmetry points of the Brillouin zone. The simulation shows that intervalley electron transfer plays a dominant role in GaN in high electric fields leading to a strongly inverted electron distribution and to a large negative differential conductance. Our simulation results have also shown that the electron velocity in GaN is less sensitive to temperature than in other III-V semiconductors like GaAs . So GaN devices are expected to be more tolerant to self-heating and high ambient temperature device modeling. Our steady state velocity-field characteristics are in fair agreement with other recent calculations.

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High-Field Electron Transport in Nanoscale Group-III Nitride Devices

physica status solidi (b) ◽

10.1002/1521-3951(200111)228:2<593::aid-pssb593>3.0.co;2-2 ◽

2001 ◽

Vol 228 (2) ◽

pp. 593-597 ◽

Cited By ~ 1

Author(s):

S.M. Komirenko ◽

K.W. Kim ◽

V.A. Kochelap ◽

M.A. Stroscio

Keyword(s):

Electron Transport ◽

High Field ◽

Group Iii ◽

Field Electron ◽

Group Iii Nitride

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Electron transport in AlN under high electric fields

MRS Proceedings ◽

10.1557/proc-693-i6.45.1 ◽

2001 ◽

Vol 693 ◽

Author(s):

Ramón Collazo ◽

Raoul Schlesser ◽

Amy Roskowski ◽

Robert F. Davis ◽

Z. Sitar

Keyword(s):

Electron Transport ◽

Energy Distribution ◽

Electric Fields ◽

Applied Field ◽

Electron Velocity ◽

Hot Electron ◽

Energy Position ◽

Aln Film ◽

High Electric Fields ◽

Hot Electron Transport

AbstractThe energy distribution of electrons transported through an intrinsic AlN film was directly measured as a function of the applied field, and AlN film thickness. Following the transport, electrons were extracted into vacuum through a semitransparent Au electrode and their energy distribution was measured using an electron spectrometer. Transport through films thicker than 95 nm and applied field between 200 kV/cm -350 kV/cm occurred as steady-state hot electron transport represented by a Maxwellian energy distribution, with a corresponding carrier temperature. At higher fields (470 kV/cm), intervalley scattering was evidenced by a multi-component energy distribution with a second peak at the energy position of the first satellite valley. Electron transport through films thinner than 95 nm demonstrated velocity overshoot under fields greater than 550 kV/cm. This was evidenced by a symmetric energy distribution centered at an energy above the conduction band minimum. This indicated that the drift component of the electron velocity was on the order of the “thermal” component. A transient length of less than 80 nm was deduced from these observations.

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The electron transport within bulk wurtzite zinc oxide in response to strong applied electric field pulses

MRS Proceedings ◽

10.1557/opl.2013.534 ◽

2013 ◽

Vol 1577 ◽

Cited By ~ 3

Author(s):

Walid A. Hadi ◽

Michael S. Shur ◽

Stephen K. O’Leary

Keyword(s):

Zinc Oxide ◽

Electron Transport ◽

Electric Field ◽

Electric Fields ◽

Drift Velocity ◽

High Field ◽

Electronic Devices ◽

Average Energy ◽

High Field Strength ◽

High Electric Fields

ABSTRACTStrong short electric field pulses are used to generate broadband terahertz radiation. Understanding the transport properties under such conditions is very important for the understanding of numerous terahertz photonic and electronic devices. In this paper, we report on transport simulations of the electrons within bulk wurtzite zinc oxide for pulsed high electric fields, with pulse durations of up to 400 fs. We focus on how key electron transport characteristics, namely the drift velocity and the corresponding average energy, vary with time since the onset of the pulse. For sufficiently high-field strength selections, we find that both of these parameters exhibit peaks. In addition, an electron drift velocity undershoot is observed following this peak. A contrast with the case of gallium nitride is considered; undershoot is not observed for the case of this material. Reasons for these differences in behavior are suggested.

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High Field Electron Drift in a-Si:H

MRS Proceedings ◽

10.1557/proc-297-425 ◽

1993 ◽

Vol 297 ◽

Author(s):

Qing Gu ◽

Eric A. Schiff ◽

Jean Baptiste Chevrier ◽

Bernard Equer

Keyword(s):

Electric Fields ◽

High Field ◽

Drift Mobility ◽

Time Range ◽

Electron Drift ◽

Parameter Change ◽

Transient Photocurrent ◽

Field Mobility ◽

High Electric Fields ◽

Electron Drift Mobility

We have measured the electron drift mobility in a-Si:H at high electric fields (E ≤ 3.6 x 105 V%cm). The a-Si:Hpin structure was prepared at Palaiseau, and incorporated a thickp+ layer to retard high field breakdown. The drift mobility was obtained from transient photocurrent measurements from 1 ns - 1 ms following a laser pulse. Mobility increases as large as a factor of 30 were observed; at 77 K the high field mobility de¬pended exponentially upon field (exp(E/Eu), where E u= 1.1 x 105 V%cm). The same field dependence was observed in the time range 10 ns – 1 μs, indicating that the dispersion parameter change with field was negligible. This latter result appears to exclude hopping in the exponential conduction bandtail as the fundamental transport mechanism in a-Si:H above 77 K; alternate models are briefly discussed.

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