Recombination Processes In Semiconductors Research Articles

PyArc: A python package for computing absorption and radiative coefficients from first principles

Light absorption and radiative recombination are two critical processes in optoelectronic materials that characterize the energy conversion efficiency. The absorption and radiative coefficients are thus key properties for device optimization and design. Here, we develop a python package named pyArc that allows rigorous computation of absorption and radiative coefficients from first principles. By integrating several interpolation strategies to augment k-point sampling in reciprocal space, our code is accurate yet highly efficient. In addition to evaluation of the coefficients, our code is capable of intuitive analysis of carrier distribution, facilitating a deeper understanding of the microscopic mechanisms underlying the radiative coefficients. Utilizing GaAs as a prototypical example, we demonstrate how to employ our package to compute absorption and radiative coefficients and to investigate the key features in the electronic structure that give rise to these coefficients. Program SummaryProgram title: PyArcCPC Library link to program files:https://doi.org/10.17632/5x9g9bvhcv.1Licensing provisions: MIT licenseProgramming language: Python 3Nature of problem: Light absorption and radiative recombination processes in semiconductors critically impact the energy conversion efficiency of optoelectronic devices. Developing a method to calculate coefficients of the two processes based on first-principles theory is essential, which not only can help to obtain the key properties of those semiconductor materials and guide the device design, but also can unveil the underlying microscopic mechanisms.Solution method: PyArc, written in the Python language, implements first-principles methodologies for the computation of absorption and radiative coefficients of semiconductors based on Fermi's golden rule. This package takes the electronic eigenvalues and dipole matrix elements of a material computed from first-principles codes such as VASP as input. Dense k-point sampling for the Brillouin zone is achieved through efficient interpolation schemes implemented in our code to acquire well converged results. The functionality of cross-sectional visualization of carrier distribution in our code provides intuitive insights into the fundamental mechanism beneath the charge-carrier radiative recombination process.

Effect stability of lifetime of charged carrier in semiconductors at a magnetic field

In work the conditions of regulation of increasing of carrier lifetime by recombination processes in semiconductors at low temperatures 1–10 K and classically «strong» magnetic fields 3 × 102 –3 × 104 Gs are analyzed. The values of carrier concentrations 1010 –1014) cm−3 correspond to conditions of manifestation as cascade as resonant capture. It is indicated on necessarily to take into account of scattering of electrons on acoustic phonons along with electron-electron collisions, by it cascade capture on coulomb centers. As showed (on the basis of concrete estimates) namely scattering on acoustic phonons at cascade capture, stabilities of lifetime and controls of dynamics it increase in the presence of «strong» magnetic field.

Compensation effect of growth of the lifetime of charged carriers in semiconductors at a magnetic field

The condition of regulation of increasing of carrier lifetime by recombination processes in semiconductors at low temperatures (1-10) K and classical "strong" magnetic fields (3·102-3·104) Gs are analyzed. The values of carrier concentrations (1010-1014) cm-3 correspond to conditions of manifestation as cascade as resonant capture. It is indicated on necessarily to take into account of scattering of electrons on acoustic phonons along with electron-electron collisions, by it cascade capture on cuolomb centers. As showed (on the basis of concrete estimates) namely scattering on acoustic phonons at cascade capture, stabilities of lifetime and controls of dynamics it increases in the presence of "strong" magnetic field. Keywords: effective coefficient of capture, cascade capture, recombination, classical "strong" magnetic field, "shallow" acoustic phonons, electron-electron collisions, lifetime.

Эффект компенсации роста времени жизни носителей заряда в полупроводниках в магнитном поле

The condition of regulation of increasing of carrier lifetime by recombination processes in semiconductors at low temperatures (1-10) K and classical "strong" magnetic fields (300-30000) Gs are analyzed. The values of carrier concentrations (10^10-10^14) cm^-3 correspond to conditions of manifestation as cascade as resonant capture. It is indicated on necessarily to take into account of scattering of electrons on acoustic phonons along with electron-electron collisions, by it cascade capture on cuolomb centers. As showed (on the basis of concrete estimates) namely scattering on acoustic phonons at cascade capture, stabilities of lifetime and controls of dynamics it increases in the presence of "strong" magnetic field.

Time constants of spin-dependent recombination processes

We present experiments to systematically study the time constants of spin-dependent recombination processes in semiconductors using pulsed electrically detected magnetic resonance (EDMR). The combination of time-programmed optical excitation and pulsed spin manipulation allows us to directly measure the recombination time constants of electrons via localized spin pairs and the time constant of spin pair formation as a function of the optical excitation intensity. Using electron nuclear double resonance, we show that the time constant of spin pair formation is determined by an electron capture process. Based on these time constants we devise a set of rate equations to calculate the current transient after a resonant microwave pulse and compare the results with experimental data. Finally, we critically discuss the effects of different boxcar integration time intervals typically used to analyze pulsed EDMR experiments on the determination of the time constants. The experiments are performed on phosphorus-doped silicon, where EDMR via spin pairs formed by phosphorus donors and Si/SiO2 interface dangling bond defects is detected.

Vladimir Idelevich Perel

Vladimir Idelevich Perel, a condensed-matter theorist who was well known for his major contributions to the spin physics in semiconductors, died of a heart attack on 11 October 2007 in Saint Petersburg, Russia.Perel was born on 24 August 1928 in Sverdlovsk (now Ekaterinburg). After high school, just after the end of World War II, he entered the physics department of the Leningrad State University, where he got his master’s degree in theoretical physics in 1950. Perel’s talents were obvious to his teachers, including Vladimir Fock, and to his fellow students, who jokingly referred to him as “professor.”Times were hard: The anti-Semitic paranoia of Joseph Stalin was gaining momentum, and Perel had already lost his father, Idel, in 1938 during the Stalin terror purges. All first jobs after graduation were assigned by special state commissions; Perel, the best student, was sent to teach physics in a small school in northern Russia, where he worked for two years. After Stalin’s death in 1953, the political climate improved, and Perel was admitted to the University of Petrozavodsk. There he did his PhD thesis on plasma physics with Yurii Kagan as his adviser. In 1958 he joined the theoretical group led by Lev Gurevich at the Ioffe Institute in Leningrad (now Saint Petersburg).Perel worked at the institute for almost 50 years, up to his last days, and was one of its emblematic personalities. His early work with Oleg Konstantinov was devoted to helicons in metals, coherence of atomic states in gases, and light polarization in electroreflectance in semiconductors. The Konstantinov—Perel diagram technique for nonequilibrium processes, developed in 1960 and widely used in the 1960s and 1970s, is especially noteworthy; a somewhat similar but better-known technique was later developed by Leonid Keldysh.In the early 1960s, condensed-matter theorists were generally excited about the application of Feynman diagrams and the mathematical methods of quantum field theory to “normal” physics. It seemed that those methods provided foolproof automatic machinery for obtaining correct solutions to any difficult problem. Perel, however, came to the conclusion that no technique can help if one doesn’t have a deep understanding of the physics involved, but when such understanding is achieved, the path to results usually becomes simple and transparent. Beginning in the 1970s, he never used his own, or any other, diagrammatic technique.Perel developed his own style of theoretical work, based on physical intuition rather than on mathematical expressions; that style greatly influenced the physics community of Saint Petersburg. Perel belonged to a rare species of theorists who could establish a mutual understanding with experimentalists. He would go into seemingly irrelevant details of an experiment and occasionally find that the origin of some “discovery” was due to an unexpected parasitic effect. He also could focus on some minor feature of the experimental data and initiate a promising direction of research.In the 1970s and early 1980s, Perel worked with one of us (Dyakonov) on optical and transport spin-related phenomena in semiconductors, a subject then regarded as esoteric but recently gaining popularity under the name “spintronics.” Their best-known achievements were the discovery of an important mechanism of spin relaxation, the explanation of the polarization properties of hot luminescence, and the theory of spectacular optical effects due to nuclear spins. Their prediction of the spin Hall effect had to wait for more than 30 years for the experimental confirmation that triggered the important theoretical and experimental activity we witness today.With Irina Yassievich and Viktor Abakumov, Perel made a major contribution to the theory of recombination processes in semiconductors. Their well-known book on that important but difficult subject, Nonradiative Recombination in Semiconductors (North-Holland, 1991), became a sort of encyclopedia for many researchers. From 1991 until his death, Perel was the editor-in-chief of the Russian journal Semiconductors and was the head of the Ioffe Institute’s group for semiconductor theory. He became a full member of the Russian Academy of Sciences in 2000. Since 1973 he worked part-time at the Leningrad Electrotechnical Institute teaching courses on solid-state physics that were exceptional for their clarity. Although those responsibilities distracted him from what he liked most—his research—he took them seriously, invariably creating an atmosphere of human decency, benevolence, and teamwork. Dozens of physicists, including the four of us, consider Perel to be their true teacher in physics. Many sought his advice and suggestions in both scientific and difficult life matters, and they felt better after talking with him. Perel presented an exceptional combination of talent, knowledge, modesty, tolerance, and the highest moral standards. Highly esteemed and loved by everyone who knew him, he will be deeply missed.Vladimir Idelevich PerelPPT|High resolution© 2008 American Institute of Physics.

Application of LTPL Investigation Methods to CVD‐Grown SiC

AbstractWe review in detail the few (simple) theoretical equations that rule all near‐equilibrium recombination processes in semiconductors with direct or indirect bandgaps. In the case of 4H‐SiC, we discuss their physical significance and show the corresponding limits. Next, we discuss the effect of residual doping in 3C‐SiC and show that, from typical low‐temperature photoluminescence (LTPL) data, very simple estimates of the doping level can be made. Finally, we focus on aluminum doping in 4H‐SiC. Performing a systematic comparison of LTPL spectra with secondary ion mass spectroscopy (SIMS) and/or capacitance‐voltage measurements, we show that a reasonably good value of the residual (or intentional) doping level can be obtained from simple optical measurements. An interesting point is that, in many cases, the use of such optical techniques offers the non‐negligible advantage to allow detection beyond the SIMS limit.

Adsorption–desorption noise in micromechanical resonant structures

In this paper we analyze adsorption–desorption (AD) noise in resonant microelectromechanical structures. This noise is generated by instantaneous differences in the rates of adsorption and desorption of contaminant molecules to and from the resonator surface, which cause mass fluctuations and consequentially frequency fluctuations. Contrary to the usual statistical approach, we used the analogy between AD processes in resonant structures and generation–recombination processes in semiconductors. Starting from that general analogy and using the theory of Langmuir’s isotherm, since it is the most convenient for this case, we derived an exact expression for the AD fluctuations-induced phase noise for the case of one adsorption layer. Our numerical results show that AD induced phase noise is comparable to other noise sources and becomes dominant for very small resonator beam dimensions. The presented theory is applicable to the determination of the limiting performance of various micromechanical resonators and microcantilever sensors and also for the theoretical studying of AD processes in general. In addition, phase noise measurements and their comparison with the theory are convenient for the investigation of catalytic AD processes.

Microwave Photomodulation Method for the Study of Recombination Processes in Semiconductors

Microwave Photomodulation Method for the Study of Recombination Processes in Semiconductors

Trapping and Recombination Properties Due to Trap Clustering

Nonequilibrium charge carriers' trapping and recombination processes in semiconductors and insulators are studied by means of the Monte Carlo method. The effect of trap clustering on trapping and recombination kinetics is considered. It is shown that such non homogeneous distribution of traps may significantly change some physical properties of a solid. The phenomena are analysed wider various conditions. The influence of the temperature, the heating program and external electric field is studied. The calculations are performed for various trap parameters and various types of correlations between traps. Comparing isothermal and non isothermal spectra one can conclude that temperature dependent phenomena - such as thermoluminescence - are more sensitive to trap clustering than their isothermal counterparts -e.g. isothermal phosphorescence decay.

Optical detection of cyclotron resonance for characterization of recombination processes in semiconductors

Abstract Novel applications of the technique of optically detected cyclotron resonance (ODCR) are discussed. This method is an extension of the conventional cyclotron resonance investigations and shows important advantages when applied to characterization of semiconductor materials. These advantages are due to a higher sensitivity and a longer momentum relaxation time caused by photoneutralization of ionized impurities. This in turn enables experiments at lower magnetic fields and lower microwave radiation frequency. Photoexcitation used in ODCR often results in a simultaneous observation of electron and hole cyclotron resonances in the same sample, which is a rare case in a conventional CR study. High magnetic field far infrared ODCR experiments utilize all these advantages of the method. For the most common X-band (10 GHz) microwave setups, the ODCR resolution often is too low to allow accurate CR determination of the band structure parameters of the material studied. In that case, ODCR may be used for ...

Steady-state trapping, detrapping, and recombination processes in semiconductors with continuous gap states

An analysis of the steady-state trapping, detrapping, and recombination processes in semiconductors with continuous gap states has provided a new formalism to view theses processes and resolved the discrepancy on steady-state recombination demarcation levels between the Rose model and the Simmons-Taylor model.

A versatile, low light level optical detection system: from time-integrated emission spectra to time-resolved, two-dimensional emission mapping

We describe a novel, low light level optical detection system that can be easily configured for various modes of operation. These include (i) time-integrated photoluminescence spectroscopy, (ii) transient, spectrally gated photoluminescence decay, (iii) time-windowed photoluminescence spectroscopy, (iv) two-dimensional, time-integrated photoluminescence mapping, and (v) time-resolved, two-dimensional photoluminescence mapping with a time resolution of ~100 ps. This new detection system is described technically and examples are given of how it can be used to study a variety of different recombination processes in semiconductors.

Low-temperature photoacoustic spectra of n-InSe

Using a ZnO transducer, two peaks at 1.250 and 1.212 eV in the photoacoustic spectra of n-InSe were obtained at 300K. The energy and its temperature variation of the 1.250 eV peak are well explained in terms of a free exciton annihilation. Another peak at 1.212 eV is interpreted by a surface related transition. The results suggest the usefulness of the low-temperature photoacoustic studies on the recombination processes in semiconductors.

Optically detected magnetic resonance (O.D.M.R.) investigations of recombination processes in semiconductors

Abstract This review covers results of recent O.D.M.R. measurements of recombination processes in layered semiconductors, II–VI compounds, at dep traps and in amorphous compounds, and includes consideration of experimental aspects.

Optical detection of magnetic resonance in semiconductors

This paper briefly reviews the application of optically detected magnetic resonance (ODMR) to the study of recombination processes in semiconductors. Investigations of spin dependent donor-acceptor, bound exciton and bound triplet exciton decay processes in crystalline materials are discussed and ODMR studies of recombination centres in amorphous silicon are briefly reported.

Three-electron recombination processes in semiconductors

A three-electron recombination process in semiconductors is analysed by employing second-order perturbation theory. Taking the unperturbed states to be planewaves and ignoring exchange effects, the recombination coefficient is calculated to be approximately /10-51 to 10-54 cm9 s-1. The overlap of the modulating parts of the Bloch functions reduce this estimate by approximately 10-3.

Erratum: “Theory of Recombination Processes in Semiconductors through Multielectron Centers with Many Excited States”

Excess carrier lifetimes are calculated under steady state conditions with explicit considerations for transitions between the various states of a multi-charged center. The results obtained are of nearly the same forms as in the usual theory in so far as a phenomenological treatment is concerned. Apparent capture probabilities of the center can be represented by probabilities of various elementary processes, and correspond to total conductances of a certain equivalent circuit. Basing upon these formulae, some studies of dynamical processes are made, and possibilities of relatively large capture cross section of repulsive centers as well as attractive ones are obtained.

Theory of Recombination Processes in Semiconductors through Multielectron Centers with Many Excited States

Excess carrier lifetimes are calculated under steady state conditions with explicit considerations for transitions between the various states of a multi-charged center. The results obtained are of nearly the same forms as in the usual theory in so far as a phenomenological treatment is concerned. Apparent capture probabilities of the center can be represented by probabilities of various elementary processes, and correspond to total conductances of a certain equivalent circuit. Basing upon these formulae, some studies of dynamical processes are made, and possibilities of relatively large capture cross section of repulsive centers as well as attractive ones are obtained.

Effect of Excited Multielectron Centers on the Recombination Processes in Semiconductors

Effect of Excited Multielectron Centers on the Recombination Processes in Semiconductors