Roman Kuzmin

Emission sensitization and mechanisms of electron-excitation migration in structures based on III-nitrides doped with rare-earth elements (Eu, Er, Sm)

The effect of doping with Eu, Er, and Sm rare-earth ions on the shape of the luminescence spectrum for heterostructures with GaN/InxGa1 − xN (0.1 < x < 0.4) quantum wells and from p-GaN〈Mg〉/n-GaN and p-AlGaN/n-GaN junctions is investigated. The results of measurements of the electroluminescence of these structures correlate with the previous data on photoluminescence and Mössbauer spectroscopy. It is shown that it is the GaN “yellow” (5000–6000 Å) band that plays the important role in the excitation of intracenter states in the structures with several GaN/InGaN quantum wells doped with Eu and Sm. In this case, Eu is most likely the sensitizer for Sm. Additional introduction of 3d metal (Fe57) in p-GaN〈Mg〉/n-GaN:Eu results in the realization of intracenter transitions in Eu3+: 5D0 → 7F1 (6006 Å), 5D0 → 7F2 (6195 Å), 5D0 → 7F3 (6627 Å), and 5D1 → 7F4 (6327 Å) due to the occurrence of new, efficient channels of excitation transfer to intracenter states and in the effect of Fe on the local environment of rare-earth ions including due to the f–d hybridization enhancement.

Infrared luminescence from silicon nanostructures heavily doped with boron

Intense highly polarized radiation from silicon nanostructures heavily doped with boron to 5 × 1021 cm−3 is studied as a function of temperature, forward current, and an additional lateral electric field. The features of the radiation intensity and degree of polarization suggest that an important role in the formation of the luminescence spectra is played by the ordered system of B+-B− dipoles, formed as a result of the reconstruction of shallow boron acceptors as centers with negative correlation energy. The results obtained are interpreted within a proposed model based on two-electron adiabatic potentials, according to which radiation results from donor-acceptor recombination via boron dipole center states, involving shallow phosphorus donors.

Defect-related luminescence in silicon p + – n junctions

Ultra-shallow p+–n junctions fabricated by the silicon planar technology based on the short-time nonequilibrium diffusion of boron from the gas phase into n-Si (100) substrates upon their preliminary oxidation and the opening of windows in SiO2 by electron lithography and reactive ion etching are examined. The electroand photoluminescence spectra measured in the study demonstrate emission in the range 1–1.6 µm, which is indicative of the presence of a high concentration of defects that probably appear as a result of the amorphizing effect of ions in the etching stage.

Features of the electroluminescence spectra of quantum-confined silicon p+-n heterojunctions in the infrared spectral region

The results of studying the characteristics of optical emission in various regions of quantum-confined silicon p+-n heterojunctions heavily doped with boron are analyzed. The results obtained allow one to conclude that near-infrared electroluminescence arises near the heterointerface between the nanostructured wide-gap silicon p+-barrier heavily doped with boron and n-type silicon (100), the formation of which included the active involvement of boron dipole centers.

Light emission from nanoscale silicon heterojunctions

The planar p+-n silicon heterojunctions are under study. The forward bias applied appears to result in the visible white light emission from p+ wide-band-gap nanostructured layer and the intensive infrared electroluminescence from the heterointerface between this nanostructured layer and the n-type Si (100) substrate.

Emission intensity in the visible and IR spectral ranges from Si-based structures formed by direct bonding with simultaneous doping with erbium (Er) and europium (Eu)

The photo- and electroluminescence spectra of silicon-based structures formed by direct bonding with simultaneous doping with rare-earth metals are studied. It is shown that emission in the visible and IR spectral ranges can be obtained from n-Si:Er/p-Si and n-Si:Eu/p-Si structures fabricated by the method suggested in the study. The results obtained make this method promising for the fabrication of optoelectronic devices.

Electrically-detected ESR in silicon nanostructures inserted in microcavities

We present the first findings of the new electrically-detected electron spin resonance technique (EDESR), which reveal the point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor delta-barriers. This technique allows the ESR identification without application of an external cavity, as well as a high frequency source and recorder, and with measuring the only response of the magnetoresistance, with internal GHz Josephson emission within frameworks of the normal-mode coupling (NMC) caused by the microcavities embedded in the Si-QW plane.

The effect of dipole boron centers on the electroluminescence of nanoscale silicon p+−n junctions

Nanoscale silicon p+−;n junctions with very high concentration of boron, 5 1021 cm−3, are found to demonstrate interesting optical properties. Emission band dominated in near-infrared electroluminescence (EL) spectra possesses high degree of the linear polarization along preferred crystallographic axis which can be controlled by the lateral voltage applied in the plane of the p+−n junction. Such behavior together with the temperature dependence of the EL intensity is attributed to the presence of the self-compensating dipole boron centers, B+-B−, with negative correlation energy which are identified using the ESR technique in the nanoscale silicon p+−n junctions heavily doped with boron. The model of the recombination process though the negative-U dipole boron centers controlling the optical properties of the nanoscale silicon p+−n junctions is proposed.

Optically detected cyclotron resonance in heavily boron-doped silicon nanostructures on n-Si (100)

Electron and hole cyclotron resonance at a frequency of 94 GHz is detected by a change in the intensity of photoluminescence lines whose positions are identical to those of dislocation luminescence lines D1 and D2 in single-crystal silicon and in heavily boron-doped silicon nanostructures on the Si (100) surface. The angular dependence of the spectrum of the optically detected cyclotron resonance corresponds to the tensor of the electron and hole effective mass in single-crystal silicon, and the resonance-line width indicates long carrier free-path times close to 100 ps. The results obtained are discussed within the framework of the interrelation of the electron-vibration coupling to charge and spin correlations in quasi-one-dimensional chains of dangling bonds in silicon.

Terahertz emission from silicon nanostructures heavily doped with boron

We present the first findings of the terahertz emission from the ultra-narrow p-type silicon quantum well confined by the δ-barriers heavily doped with boron on the n-type Si (100) surface. The THz spectra revealed by the voltage applied along the Si-QW plane appear to result from the radiation of the dipole boron centers.