Submicron Heterostructures for Microelectronics Research and Engineering Center

Micropillar cavity lasers demonstrate operation up to 255 K. At this temperature, the lasing threshold and Q-factor, extracted at lasing threshold for a 4 μm diameter pillar are about 2 mW and 16800. For pillar lasers, the concept of which is based on an optical aperture, continuous-wave lasing is realized at room temperature (300 K). For a 15 μm diameter pillar with an aperture of 4 μm, single-mode lasing at 960 nm is demonstrated with a threshold power of about 12 mW and a Q-factor at threshold of 13000.

The paper presents the results of investigating the static characteristics of avalanche photodiodes (APD) fabricated from an InP/InGaAs heterostructure grown by metal organic vapor phase epitaxy, followed by single-stage zinc diffusion from a metal organic source of diethylzinc. The fabricated APDs have demonstrated at room temperature a breakdown voltage of 53 V, dark currents of maximum 0.7 nA, and a capacitance of 0.55 pF at 0.9 times the breakdown voltage. The spectral sensitivity of the fabricated APD was at least 0.8 A/W at a wavelength of 1550 nm. The temperature coefficient of the APD breakdown voltage was 85 mV/K.

Point defects were controllably introduced into 270 nm AlGaN Light-Emitting Diodes (LEDs) by 5 MeV electron and 1.1 MeV proton irradiations to examine the effect on electrical and luminescent characteristics. The 5 MeV electron irradiations had only a marginal effect on the charge distribution, current flow, and electroluminescence of LEDs for electron fluences up to 4.5 × 1016 e/cm2 that cause very strong degradation in green, blue, and near-UV LEDs. This lack of changes is attributed to the much higher charge densities in quantum-wells (QWs) and quantum barriers (QBs) of the 270 nm LEDs and to higher bond strength in high Al mole fraction AlGaN layers. By contrast, irradiation with 1.1 MeV protons with a fluence of 1016 p/cm2 leads to more than two orders of magnitude decrease in charge density in the QWs and QBs, a strong increase in the series resistance, and the emergence of deep electron traps near Ec-0.5 eV. The difference is explained by a much higher density of primary defects produced by protons. The observed effects are compared to changes in performance caused by aging after high driving current.

Bandgap engineering in III-V ternary materials and nanostructures of different types (nanoislands, nanomembranes, vapor-liquid-solid (VLS) and catalyst-free nanowires (NWs)) requires precise compositional tuning by vapor fluxes. Here, we develop a fully self-consistent growth model for the vapor-solid and VLS pseudo-binary $\mathrm{A}_{\mathrm{x}} \mathrm{B}_{1-\mathrm{x}} \mathrm{C}$ nanomaterials and show that the vapor-solid distribution can be tuned from the equilibrium to kinetic Langmuir-McLean shape by decreasing the total $(\mathrm{A}+\mathrm{B}) / \mathrm{C}$ flux ratio. We demonstrate the excellent fits by the model of a wide range of available data for AlSbAs epilayers, InSbAs, InAsP and GaAsP NWs grown by different techniques under different total V/III flux ratios in vapor.

A decrease in external quantum efficiency (EQE) of commercial LEDs based on MQW InGaN/GaN at wavelengths of 445, 530 and MQW AlGaN/GaN at 280 nm was experimentally studied in the standard aging mode at direct current. The decrease in EQE (regardless of the radiation wavelength) is found out to occur due to cooperative phenomena developing in 1–2 quantum wells (QWs) located in the space charge region (SCR) around the p–n junction, as well as in most of the QWs outside of SCR. It is shown that the inhomogeneous flow of current in these regions leads not only to the transformation of defects localized at heteroboundaries in the SCR and in lateral inhomogeneities in the alloy composition outside of SCR as well as in the extended defects, but also to a change in the alloy composition.

At 340 K, the Ohmic contact of Cr with nondegenerate InAs caused a cooling of 1 K of the chip body.

The influence of the substrate temperature and the flux of In adatoms on the structural and optical characteristics of InAs quantum dots with a low surface density is experimentally studied. An increase in the substrate temperature under conditions of a high flux of In adatoms promotes an increase in their surface migration and a certain decrease in the density of the array of quantum dots (down to ~(1–2) × 1010 cm–2), however, in this case a significant short-wavelength shift of the photoluminescence spectrum is observed despite an increase in lateral sizes of dots. A decrease in the incident flux of In adatoms at optimal substrate temperatures makes it possible to reduce the dot density more efficiently (down to ~(1–2) × 109 cm–2).

Abstract—The possibility of using vertical-emitting lasers with intracavity contacts (IC-VCSEL) and a rhomboidal oxide current aperture for creating a non-zero magnetic field optically pumped atomic magnetometers (OPM) with a 133Cs vapor cell for magnetoencephalographic (MEG) systems were demonstrated. Relative intensity noise (RIN) and polarization resolved RIN of the IC-VCSEL in the 895 nm range with different mirror losses (linewidth) in the frequency range from 1Hz to 100 kHz were experimentally investigated. Lasers with low mirror loss (narrow linewidth) have polarization resolved RIN comparable to amplitude noise. For IC-VCSEL with an output optical power of 0.8 mW and a linewidth of 55 MHz, the noise level measured is 148 dB/Hz in 1 Hz bandwidth at 40 kHz frequency. The ultimate sensitivity of OPM based on two-beam MZ-scheme with studied VCSELs was estimated as ~11 fT/ $$\sqrt {{\text{Hz}}} $$ .

Study of Ga2O3 deposition by MOVPE using trimethylgallium and oxygen was performed in a wide temperature range. It was found that for Ga2O3 deposition rate vs temperature dependence is very close to the TMGa pyrolysis in nitrogen. Kinetically-limited range for these processes corresponds to 550–700°C, that is 150°C higher, then for GaN deposition in the same reactor.

We propose a method of analysis of spontaneous emission of a quantum emitter (an atom, a luminescence center, a quantum dot) inside or in vicinity of a cylinder. At the focus of our method are analytical expressions for the scattering matrix of the cylindrical nanoobject. We propose the approach to electromagnetic field quantization based of eigenvalues and eigenvectors of the scattering matrix. The method is applicable for calculation and analysis of spontaneous emission rates and angular dependences of radiation for a set of different systems: semiconductor nanowires with quantum dots, plasmonic nanowires, cylindrical hollows in dielectrics and metals. Relative simplicity of the method allows obtaining analytical and semi-analytical expressions for both cases of radiation into external medium and into guided modes.