Optical Transitions Involving Impurities in Semiconductors

Dumke, W. P.

doi:10.1103/physrev.132.1998

Cited by 260 publications

(59 citation statements)

References 9 publications

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“…The energy levels of shallow impurities in extrinsic semiconductors represent localized electronic states which strongly affect the optical and electrical properties of the material. Dipole-allowed transitions between the ground state of impurities and delocalized states in the valence and conduction bands result in distinct absorption and emission bands [1]. For charge transport at high electric fields, repeated scattering of carriers between continuum states and the excited levels of the impurities, i.e., carrier trapping and impurity ionization, reduces the conductivity of the material.…”

Section: Picosecond Capture Of Photoexcited Holes By Shallow Acceptormentioning

confidence: 99%

Picosecond capture of photoexcited holes by shallow acceptors inp-type GaAs

et al. 1992

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Ultrafast recombination of holes with shallow acceptors in a III-V semiconductor is directly observed for the first time, by means of picosecond infrared spectroscopy. Neutral impurities in p-doped GaAs at low temperature are photoionized by picosecond infrared excitation. The recombination of free holes with negatively charged acceptors-monitored via absorption changes below the band edge-occurs on a time scale of several tens of picoseconds, following a nonexponential kinetics. Emission of longitudinaloptical phonons by the free holes is found to be the dominant mechanism of recombination.PACS numbers: 71.55.Eq, 78.30.Fs The energy levels of shallow impurities in extrinsic semiconductors represent localized electronic states which strongly affect the optical and electrical properties of the material. Dipole-allowed transitions between the ground state of impurities and delocalized states in the valence and conduction bands result in distinct absorption and emission bands [1]. For charge transport at high electric fields, repeated scattering of carriers between continuum states and the excited levels of the impurities, i.e., carrier trapping and impurity ionization, reduces the conductivity of the material. Those processes are particularly relevant at low temperatures and high doping densities where a certain fraction of impurities is ionized [2].In the early cascade-capture model, carrier trapping is described as emission of a sequence of single acoustic phonons, followed by a final relaxation to the impurity ground state [3]. Refined theoretical treatments have been developed to account for multiple scattering and have calculated cross sections of carrier capture [2]. More recently, Monte Carlo techniques have been used to simulate the kinetics of charge transport [2,4]. Extensive experimental work has concentrated on stationary transport or electrical noise measurements giving capture cross sections for shallow donors and acceptors in silicon and germanium [5]. In contrast, very limited information exists on the microscopic dynamics of carrier capture. Nanosecond trapping times have been deduced from time-resolved transport studies on n-type germanium [6] and from the photo-Hall effect of p-type silicon [7]. In GaAs, time-resolved studies of impurity related luminescence report electron and hole capture on a time scale between 10 and 500 ns [8]. The observed relaxation rates are mainly determined by the interaction between free carriers of low kinetic energy and acoustic phonons [2]. In GaAs and other III-V semiconductors, the interaction with optical phonons is much stronger than the acoustic deformation potential. Thus enhanced capture rates should occur if electrons and holes have sufficient energy to emit longitudinal (LO) or transversal (TO) optical phonons. Furthermore, the large energy of the optical phonons compared to acoustic phonons allows the direct population of the ground state of a shallow impurity by emission of a single optical phonon if the phonon energy is higher than the ionization ene...

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Section: Picosecond Capture Of Photoexcited Holes By Shallow Acceptormentioning

confidence: 99%

Picosecond capture of photoexcited holes by shallow acceptors inp-type GaAs

et al. 1992

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“…In indirect bandgap semiconductors, indirect transitions contribute to loss for photon energies exceeding the bandgap before the direct transitions set in. For photon energies below the bandgap, there can be appreciable losses due to various mechanisms such as trap-assisted transitions (eXgX nitrogen levels in GaP:N [68]), generation of excitons (especially for wide bandgap semiconductors and insulators [69][70][71]) and transitions between impurity levels [72].…”

Section: Introductionmentioning

confidence: 99%

Searching for better plasmonic materials

West

Ishii

Naik

et al. 2010

Laser & Photonics Reviews

1,894

1,522

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Plasmonics is a research area merging the fields of optics and nanoelectronics by confining light with relatively large free-space wavelength to the nanometer scale -thereby enabling a family of novel devices. Current plasmonic devices at telecommunication and optical frequencies face significant challenges due to losses encountered in the constituent plasmonic materials. These large losses seriously limit the practicality of these metals for many novel applications. This paper provides an overview of alternative plasmonic materials along with motivation for each material choice and important aspects of fabrication. A comparative study of various materials including metals, metal alloys and heavily doped semiconductors is presented. The performance of each material is evaluated based on quality factors defined for each class of plasmonic devices. Most importantly, this paper outlines an approach for realizing optimal plasmonic material properties for specific frequencies and applications, thereby providing a reference for those searching for better plasmonic materials.

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“…͑19͔͒ can be adapted for donor-to-valence-band transitions by replacing the effective masses and acceptor binding energy instead of the donor binding energy. 71 In the 3D case, the absorption coefficient for the acceptor free electron transition obeys…”

Section: ͑18͒mentioning

confidence: 98%

Excitonic and impurity-related optical transitions in Beδ-dopedGaAs∕AlAsmultiple quantum wells: Fractional-dimensional space approach

Kundrotas¹,

Čerškus²,

Ašmontas³

et al. 2005

Phys. Rev. B

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We have investigated the optical transitions in Be ␦-doped GaAs/ AlAs multiple quantum wells with various width and doping levels. The fractional dimensionality model was extended to describe free-electron-acceptor ͑free hole-donor͒ transitions in a quantum well. The measured photoluminescence spectra from the samples were interpreted within the framework of this model, and acceptor-impurity induced effects in the photoluminescence line shapes from multiple quantum wells of different widths were demonstrated.

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Optical Transitions Involving Impurities in Semiconductors

Cited by 260 publications

References 9 publications

Picosecond capture of photoexcited holes by shallow acceptors inp-type GaAs

Picosecond capture of photoexcited holes by shallow acceptors inp-type GaAs

Searching for better plasmonic materials

Excitonic and impurity-related optical transitions in Beδ-dopedGaAs∕AlAsmultiple quantum wells: Fractional-dimensional space approach

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