Search

The effect of ion energy in a focused ion beam in the range 12–30 keV on the formation depth of nonradiative recombination centers during etching of the Al0.18Ga0.82As/GaAs/Al0.18Ga0.82As double heterostructure has been studied. It is shown that an increase in the ion energy leads to an increase in the concentration and propagation depth of radiation defects. It was found that during etching of focused ion beam with ion energies above 15 keV, the depth of formation of radiation defects exceeds 900 nm, which does not correspond to the calculations in the Stopping and Range of Ions in Matter. [ABSTRACT FROM AUTHOR]

The paper presents a procedure for creating on GaAs(100) substrates textured surfaces by ion-beam etching with a focused beam. The possibility of flexibly controlling the shape and profile of the formed submicron elements of textured media is shown; this will later allow formation of textured surfaces of almost any complexity for realizing the surface radiation coupling from the waveguide. Original lithographic masks were developed, and 3D lithography was accomplished. The obtained lithographic patterns were controlled by the methods of optical, electron and atomic force microscopy. [ABSTRACT FROM AUTHOR]

Light-emitting devices of modern photonics are based on the semiconductor structures containing layers with various physical parameters. To preserve initial parameters during focused ion beam (FIB) lithography, it is necessary to take into account the processes of radiation defect formation. Radiation-induced defects in target play role of nonradiative recombination centers leading to photoluminescence (PL) quenching. In our work, the FIB impact on the photoluminescence were examined using PL spectroscopy of milled Al0.18Ga0.82As/GaAs double heterostructure. In order to exclude photoexcited carriers losses in emitter layer, an experiment with subbarrier photoexcitation was organized. Finally, we compare our experimental findings with theoretical data proposed by stopping and range of ions in matter (SRIM) calculation. [ABSTRACT FROM AUTHOR]

A new approach for calculating the ion dose spatial distribution of the focused ion beam is proposed. The approach is based on the analysis of the secondary electron microscopy image of the area irradiated by the focused ion beam. [ABSTRACT FROM AUTHOR]

The work presents experimental data of Ga+ focused ion beam etching of disc and ring patterns in Si3N4/GaN structure. The reasons for the difference in etching depth between the discs and the rings are described. [ABSTRACT FROM AUTHOR]

The ion-beam etching of AlGaAs/GaAs heterostructures gives rise to radiation defects and, as a result, leads to photoluminescence quenching. Annealing at 620°C in an atmosphere of As almost completely restores the quantum efficiency of photoluminescence in the case of radiation-induced defects lying at a distance of up to 150 nm from the heterointerface. [ABSTRACT FROM AUTHOR]

We studied the influence of the focused ion beam milling of ridge waveguides on lasing parameters of edge-emitting lasers, based on a separate confinement double heterostructure. It is shown that there are three degrees of influence, according to the etching depth: modification of the waveguide properties only, a decrease in efficiency without changing the threshold current, and a simultaneous deterioration in the threshold current and efficiency with significant modification of the optical characteristics of the laser. [ABSTRACT FROM AUTHOR]

The results of studies of 7.5–8.0 μm range surface-emitting ring quantum-cascade lasers are presented. A second- order diffraction grating with a calculated coupling coefficient of ~9 cm–1 is formed on the entire surface of the ring cavity by focused ion beam milling. Surface-emitting lasing at room temperature near 7.75 μm with a threshold current density of ~8 kA/cm2 and an outer radius of the ring cavity of 202 μm is demonstrated. The results of studying the intensity distribution in the far-field near the normal to the surface showed the presence of two maxima. It is shown that the implemented coupling coefficient is not sufficient to ensure single-mode lasing in the studied ring quantum-cascade lasers. [ABSTRACT FROM AUTHOR]

The results of studies of ring quantum-cascade lasers with surface emission due to a second-order grating formed in the top cladding layers are presented. Surface emission near 7.85 μm with a low threshold current density (3.8 kA/cm2), in comparison with ridge quantum-cascade lasers of the same cavity length is demonstrated. The results of measurements of the intensity distribution of the near and far fields at different pumping levels are presented. The estimated value of the angle of beam extraction relative to the surface normal is in the range 5.7°–6.7°. [ABSTRACT FROM AUTHOR]

Abstract: Our study describes FIB technological aspects of preparing mask for GaN selective area epitaxy on Si3N4/GaN template. [ABSTRACT FROM AUTHOR]

Abstract: We present results of experiments concerning the loss of internal quantum efficiency of the GaAs/AlGaAs heterostructure due to the focused ion beam-induced radiation defects. Firstly we show that 300°C annealing in the high vacuum conditions leads to a partial recovery of the internal quantum efficiency and, therefore, photoluminescence regains some of its intensity. Secondly we show that 620°C annealing in the presence of As vapor leads up to 80% recovery of the internal quantum efficiency depending on the etching depth. Achieved results proves focused ion beam technique to be potent for the fabrication of photonic structures based on A3B5 materials containing active layer. [ABSTRACT FROM AUTHOR]

In the Si3N4 layer, coaxial and single submicrometer GaN structures of hexagonal shape with pyramidal facets are formed by selective vapor-phase epitaxy in windows produced with a focused ion beam. It is found that coaxial hexagonal structures are formed during the growth process in ring-shaped mask windows. [ABSTRACT FROM AUTHOR]

We study and compare optical microcavities formed by GaN planar nanowires. Nanostructures with structural defects such as stacking faults and without defects are considered. The behavior of an exciton localized in a stacking fault is considered. Different behavior of the photoluminescence intensity and the photoluminescence decay time is observed for the cases under consideration. Theoretical calculations show the localization of the field at the ends of the structure. [ABSTRACT FROM AUTHOR]

The results of studying a ring surface-emitting quantum-cascade laser with radiation emission through a textured layer formed in the layers of the upper cladding of the waveguide by ultrahigh-vacuum ion-beam milling are presented. The far-field profile shows that the radiation is emitted through windows with a textured layer in the range of angles ~63°–75° to the surface normal. [ABSTRACT FROM AUTHOR]

Quantum-cascade lasers with surface emission of radiation by means of a grating formed in the upper waveguide cladding layers by ion-beam milling are fabricated and studied. The active region of the laser heterostructure is based on the In0.53Ga0.47As/Al0.48In0.52As alloy alloys and uses a design with two-phonon resonance emptying of the lower level in the cascade. Room-temperature lasing near 7.9 μm is demonstrated for a laser with a ring-cavity diameter of 191 μm. The mode spacing in the lasing spectra corresponds to whispering-gallery modes. [ABSTRACT FROM AUTHOR]

We have created a quantum-cascade laser with 7–8 μm wavelength and surface radiation output through a lattice formed by focused ion beam etching of the upper cladding of the waveguide. The active area of the quantum-cascade laser heterostructure was formed on the basis of the solid alloy heteropair In0.53Ga0.47As/Al0.48In0.52As with two-phonon depletion of the cascade lower level. We demonstrate laser generation in the spectral band 7–8 μm for the created lasers with the selective ring resonator. The studies of the generation spectra for the temperatures in 8–77 K range have shown, that the mode spacing in the generation spectra of these lasers correspond to the whispering-gallery modes. [ABSTRACT FROM AUTHOR]

Single-mode lasing of quantum-cascade lasers with a distributed Bragg reflector formed by ion-beam etching in layers of the upper waveguide cladding is demonstrated. The active region is formed based on an In0.53Ga0.47As/Al0.48In0.52As solid-alloy heteropair with two-phonon depletion of the lower level in the cascade. Single-mode lasing at a temperature of 280 K corresponds to the emission wavelength of 7.74 μm, and the side-mode suppression ratio is 24 dB. [ABSTRACT FROM AUTHOR]

The effect of annealing temperature and time on the luminescence intensity of the InGaN/GaN heterostructure subjected to ion beam etching was studied. We show that annealing at a temperature of 1100°C makes it possible to eliminate the radiation defects in the GaN layers that arise in the etching process with a focused Ga+ ion beam (30 keV). [ABSTRACT FROM AUTHOR]

We present an approach for the treatment of coupled-ridge lasers using focused ion beam⁠ (FIB) etching. We show experimentally that the FIB etching allows post-processing lateral mode tuning without deterioration of the main laser parameters. [ABSTRACT FROM AUTHOR]

The effect of the growth temperature and the flow of trimethylgallium on the process of selective epitaxy of gallium nitride in windows of submicron size have been studied. The conditions under which homogeneous nucleation and coalescence of nuclei are combined with a low growth rate are determined. The steady growth of variously oriented gallium nitride strips with a height of 50 nm and a width of 600 nm was realized. [ABSTRACT FROM AUTHOR]