Impact ionization and field-enhanced trapping: Fitting current density curves for semi-insulating GaAs

Albuquerque, Holokx A.; Oliveira, A. G. de; Silva, R. L. da; Rodrigues, Wagner Nunes; Moreira, M. V. B.; Rubinger, R. M.

doi:10.1063/1.1534892

Cited by 10 publications

(3 citation statements)

References 13 publications

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“…Indeed, IMP is one of the most important processes in semiconductor devices at high field and in the avalanche phenomena, and cross sections for impact ionization are needed as input data of the Boltzmann transport equation. This approach provides the transport coefficients computed from the non-equilibrium distribution function obtained using a particle-based (Monte Carlo) numerical model [170][171][172][173][174]. Input scattering cross sections are computed for the system at equilibrium, within the Born approximation.…”

Section: Impact Ionizationmentioning

confidence: 99%

Hot electron relaxation dynamics in semiconductors: assessing the strength of the electron–phonon coupling from the theoretical and experimental viewpoints

Sjakste

Tanimura

Barbarino

et al. 2018

J. Phys.: Condens. Matter

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The rapid development of the computational methods based on density functional theory, on the one hand, and of time-, energy-, and momentum-resolved spectroscopy, on the other hand, allows today an unprecedently detailed insight into the processes governing hot-electron relaxation dynamics, and, in particular, into the role of the electron-phonon coupling. Instead of focusing on the development of a particular method, theoretical or experimental, this review aims to treat the progress in the understanding of the electron-phonon coupling which can be gained from both, on the basis of recently obtained results. We start by defining several regimes of hot electron relaxation via electron-phonon coupling, with respect to the electron excitation energy. We distinguish between energy and momentum relaxation of hot electrons, and summarize, for several semiconductors of the IV and III-V groups, the orders of magnitude of different relaxation times in different regimes, on the basis of known experimental and numerical data. Momentum relaxation times of hot electrons become very short around 1 eV above the bottom of the conduction band, and such ultrafast relaxation mechanisms are measurable only in the most recent pump-probe experiments. Then, we give an overview of the recent progress in the experimental techniques allowing to obtain detailed information on the hot-electron relaxation dynamics, with the main focus on time-, energy-, and momentum-resolved photoemission experiments. The particularities of the experimental approach developed by one of us, which allows to capture time-, energy-, and momentum-resolved hot-electron distributions, as well as to measure momentum relaxation times of the order of 10 fs, are discussed. We further discuss the main advances in the calculation of the electron-phonon scattering times from first principles over the past ten years, in semiconducting materials. Ab initio techniques and efficient interpolation methods provide the possibility to calculate electron-phonon scattering times with high precision at reasonable numerical cost. We highlight the methods of analysis of the obtained numerical results, which allow to give insight into the details of the electron-phonon scattering mechanisms. Finally, we discuss the concept of hot electron ensemble which has been proposed recently to describe the hot-electron relaxation dynamics in GaAs, the applicability of this concept to other materials, and its limitations. We also mention some open problems.

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Section: Impact Ionizationmentioning

confidence: 99%

Hot electron relaxation dynamics in semiconductors: assessing the strength of the electron–phonon coupling from the theoretical and experimental viewpoints

Sjakste

Tanimura

Barbarino

et al. 2018

J. Phys.: Condens. Matter

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“…Furthermore, the fitting curve of J(E) can be achieved from the analytical expression in Ref. [24] by considering all of the five critical fields mentioned above. Here the current density J is expressed as a function of electric field E J…”

Section: Critical Fieldmentioning

confidence: 99%

Roles of voltage in semi-insulating GaAs photoconductive semiconductor switch

Cui

Yang

et al. 2017

Chinese Phys. B

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An experimental study of leakage current is presented in a semi-insulating (SI) GaAs photoconductive semiconductor switch (PCSS) with voltages up to 5.8 kV (average field is 19.3 kV/cm). The leakage current increases nonlinearly with the bias voltage increasing from 1.2×10 −9 A to 3.6×10 −5 A. Furthermore, the dark resistance, which is characterized as a function of electric field, does not monotonically decrease with the field but displays several distinct regimes. By eliminating the field-dependent drift velocity, the free-electron density n is extracted from the current, and then the critical field for each region of n(E) characteristic of PCSS is obtained. It must be the electric field that provides the free electron with sufficient energy to activate the carrier in the trapped state via multiple physical mechanisms, such as impurity ionization, fielddependent EL2 capture, and impact ionization of donor centers EL10 and EL2. The critical fields calculated from the activation energy of these physical processes accord well with the experimental results. Moreover, agreement between the fitting curve and experimental data of J(E), further confirms that the dark-state characteristics are related to these field-dependent processes. The effects of voltage on SI-GaAs PCSS may give us an insight into its physical mechanism.

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“…In the second one, the current has a V 2 dependence associated with space-charge-dominated transport. For higher applied bias, one enters the third region, where negative differential conductance (NDC) is present and current oscillations may take place [8]. Above that voltage range, breakdown is reached, producing a sudden increase of the current phenomenon associated with impact ionization [9], [10].…”

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confidence: 99%

Influence of Laser Modulation Frequency on the Performance of Terahertz Photoconductive Switches on Semi-Insulating GaAs Exhibiting Negative Differential Conductance

Paz-Martínez

Treviño‐Palacios

Molina

et al. 2021

IEEE Trans. THz Sci. Technol.

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In typical terahertz time-domain spectroscopy systems, the use of the lock-in technique is necessary because of the low current induced at the receiver so that the laser pump beam must be modulated (chopped) at a frequency much lower than the laser repetition rate. This work shows that, in the case of semi-insulating GaAs (SI-GaAs) antennas, this modulation has an important effect on the antenna current and consequently, on the radiated electromagnetic pulse. There exists a threshold bias (whose value depends on the chopping frequency) where an abrupt increase in the current and consequently, in the terahertz emission takes place. The calculated energy of the pulse below and above the threshold shows that the energy doubles. The exact bias voltage at which this occurs changes with the laser modulation frequency when this is below 350 Hz, but at higher frequencies, the threshold remains almost constant. The experiments show that the responsibility for this behavior is the S-shape negative differential conductance exhibited by SI-GaAs originated by a slow field-enhanced charge trapping mechanism, which is also an important source of noise at the receiver of the system. Index Terms-Negative differential conductance (NDC), photoconductive switch, terahertz time-domain spectroscopy (THz-TDS). I. INTRODUCTIONO VER the past years, there has been an increase of new applications at terahertz (THz) frequencies for which Manuscript

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Impact ionization and field-enhanced trapping: Fitting current density curves for semi-insulating GaAs

Cited by 10 publications

References 13 publications

Hot electron relaxation dynamics in semiconductors: assessing the strength of the electron–phonon coupling from the theoretical and experimental viewpoints

Hot electron relaxation dynamics in semiconductors: assessing the strength of the electron–phonon coupling from the theoretical and experimental viewpoints

Roles of voltage in semi-insulating GaAs photoconductive semiconductor switch

Influence of Laser Modulation Frequency on the Performance of Terahertz Photoconductive Switches on Semi-Insulating GaAs Exhibiting Negative Differential Conductance

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