Nonequilibrium drift-diffusion transport in semiconductors in presence of strong inhomogeneous electric fields

Zakhleniuk, N. A.

doi:10.1063/1.2420787

Cited by 10 publications

(5 citation statements)

References 16 publications

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“…The other option is to use the Monte Carlo method, but this is again impractical for many real devices. There were also some suggestions [26,27] on how to include the non-local effects in calculating non-equilibrium kinetic coefficients, like mobility or diffusivity, but these approaches have not been implemented yet into numerical models.…”

Section: Resultsmentioning

confidence: 99%

Overshoot mechanism in transient excitation of THz and Gunn oscillations in wide-bandgap semiconductors

2012

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A detailed study of high-field transient and direct-current (DC) transport in GaN-based Gunn diode oscillators is carried out using the commercial simulator Sentaurus Device. Applicability of drift-diffusion (DD) and hydrodynamic (HD) models to high-speed, high-frequency devices is discussed in depth, and the results of the simulations from these models are compared. It is shown, for a highly homogeneous device based on a short (2 μm) supercritically doped (1017 cm−3) GaN specimen, that the DD model is unable to correctly take into account some essential physical effects which determine the operation mode of the device. At the same time, the HD model is ideally suited to solve such problems due to its ability to incorporate non-local effects. We show that the velocity overshoot near the device contacts and space charge injection and extraction play a crucial role in defining the operation mode of highly homogeneous short diodes in both the transient regime and the voltage-controlled oscillation regime. The transient conduction current responses are fundamentally different in the DD and HD models. The DD current simply repeats the velocity-field (v-F) characteristics, and the sample remains in a completely homogeneous state. In the HD model, the transient current pulse with a full width at half maximum of approximately 0.2 ps is increased about twofold due to the carrier injection (extraction) into (from) the active region and the velocity overshoot. The electron gas is characterized by highly inhomogeneous distributions of the carrier density, the electric field and the electron temperature. The simulation of the DC steady states of the diodes also shows very different results for the two models. The HD model shows the trapped stable anodic domain in the device, while the DD model completely retains all features of the v-F characteristics in a homogeneous gas. Simulation of the voltage-controlled oscillator shows that it operates in the accumulation layer mode generating microwave signals at 0.3 to 0.7 THz. In spite of the fact that the known criterion of a Gunn domain mode n0L > (n0L)0 was satisfied, no Gunn domains were observed. The explanation of this phenomenon is given.

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Section: Resultsmentioning

confidence: 99%

Overshoot mechanism in transient excitation of THz and Gunn oscillations in wide-bandgap semiconductors

2012

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“…In general, the sample‐specific dependence of the drift‐diffusion velocity on local electric fields 40 is of utmost importance to investigate the frequency dependence for any sample and for any KPFM system before attempting a quantitative interpretation of the measured KPFM bias exclusively based on the removal of the asymmetric electric dipole.…”

Section: Discussionmentioning

confidence: 99%

Kelvin probe force microscopy in the presence of intrinsic local electric fields

Baumgart

Müller²,

Müller³

et al. 2011

Physica Status Solidi (a)

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Kelvin probe force microscopy (KPFM) is used to investigate the electrostatic force between a conductive probe and doped semiconductors. The observed frequency dependence of the probed KPFM bias is strongly related to sample‐specific intrinsic local electric fields. Equilibrium drift and diffusion of excess charge carriers at low operation frequencies influence the characteristics of the asymmetric electric dipole in the surface region of the investigated semiconductors during the KPFM measurement. The sample‐specific KPFM background signal does not influence the frequency‐dependent lateral variation of the electrical signal. The KPFM bias probed on doped semiconductor nanostructures with high or small enough operation frequencies allows for quantitative dopant profiling or investigation of diffusion processes in internal electric fields, respectively.

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“…The numerical simulation environment is critical for the generation of accurate results with reasonable calculation times. Several physical models of analytic concentration-dependent mobility (ANALYTIC) [31,32], field-dependent mobility (FLDMOB) [33], Shockley-Read-Hall recombination (SRH) [34,35], Auger recombination (AUGER) [36], and band gap narrowing (BGN) [37] were used in this work. These models can be used to calculate the field, doping concentration, and temperature-dependent mobility and current.…”

Section: Depth (μM)mentioning

confidence: 99%

Gate Current and Snapback of 4H-SiC Thyristors on N+ Substrate for Power-Switching Applications

et al. 2020

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High-power switching applications, such as thyristor valves in a high-voltage direct current converter, can use 4H-SiC. The numerical simulation of the 4H-SiC devices requires specialized models and parameters. Here, we present a numerical simulation of the 4H-SiC thyristor on an N+ substrate gate current during the turn-on process. The base-emitter current of the PNP bipolar junction transistor (BJT) flow by adjusting the gate potential. This current eventually activated a regenerative action of the thyristor. The increase of the gate current from P+ anode to N+ gate also decreased the snapback voltage and forward voltage drop (Vf). When the doping concentration of the P-drift region increased, Vf decreased due to the reduced resistance of a low P-drift doping. An increase in the P buffer doping concentration increased Vf owing to enhanced recombination at the base of the NPN BJT. There is a tradeoff between the breakdown voltage and forward characteristics. The breakdown voltage is increased with a decrease in concentration, and an increase in drift layer thickness occurs due to the extended depletion region and reduced peak electric field.

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Nonequilibrium drift-diffusion transport in semiconductors in presence of strong inhomogeneous electric fields

Cited by 10 publications

References 16 publications

Overshoot mechanism in transient excitation of THz and Gunn oscillations in wide-bandgap semiconductors

Overshoot mechanism in transient excitation of THz and Gunn oscillations in wide-bandgap semiconductors

Kelvin probe force microscopy in the presence of intrinsic local electric fields

Gate Current and Snapback of 4H-SiC Thyristors on N+ Substrate for Power-Switching Applications

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