Selective oxidation of AlGaAs aperture layers of a Vertical-cavity surface-emitting laser with a generation wavelength of 850 nm

A study of the technology of selective oxidation of the buried AlGaAs layer used as an aperture layer in the structure of a Vertical-cavity surface-emitting laser has been carried out. Oxidation process was made as thermal oxidating in a humidified nitrogen atmosphere. The conditions of the oxidation process are described, images of the oxidation results and the dependence of the growth rate of the oxidized layer on the process temperature are presented. A technology for the formation of an oxide current aperture has been developed for vertical cavity surface emitting lasers with a generation wavelength of 850 nm, which makes it possible to accurately control the size and shape of the resulting aperture.

Особенности транспорта носителей заряда в структурах n-=SUP=-+-=/SUP=--n-=SUP=-0-=/SUP=--n-=SUP=-+-=/SUP=- с гетеропереходом GaAs/AlGaAs при сверхвысоких плотностях тока

The current–voltage characteristics of n ^+-GaAs/ n ^0-GaAs/ N ^0-AlGaAs/ N ^+-AlGaAs/ n ^+-GaAs isotype heterostructures and n ^+-GaAs/ n ^0-GaAs/ n ^+-GaAs homostructures are studied. It is shown that, for a heterostructure under reverse bias providing the injection of electrons from n ^0-GaAs into N ^0-AlGaAs, the maximum operating voltage reaches a value of 48 V at a thickness of the N ^0-AlGaAs layer of 1 . 0 μm, and the current–voltage characteristic has no region of negative differential resistance. The operation of a homostructure is accompanied by a transition to the negative-differential-resistance region at a voltage of 10 V. Theoretical analysis in terms of the energy-balance model demonstrated that the reverse-biased isotype heterostructure has no negative-differential-resistance region because, in this case, the field domain does not collapse in contrast to what occurs in homostructures.

Confinement Barrier Induced Enhancement in Thermal Stability of the Optical Response of InAs/InGaAs/GaAs Submonolayer Quantum Dot Heterostuctures

In this study the improvement in thermal stability of optical properties of InAs submonolayer quantum dot (SML QD) heterostructures is observed through incorporation of symmetric AlGaAs barrier layers. Low temperature photoluminescence (PL) spectra shows blue shift with less full width at half maxima, ascribe to the assimilation of AlGaAs barrier layers. The sample with confinement enhancing barrier shows the highest ground to ground transition energy with the lowest dot size distribution. Ex situ annealing of as grown samples, followed by PL analysis, confirms the improvement in thermal stability of optical behavior. For the samples with symmetric AlGaAs layer, annealing at higher temperatures under an inert condition can not change the downward transition energy effectively, whereas normal DWELL structures exhibits significant blue shift for the same.

PHOTOCAPACITANCE OF SELECTIVELY DOPED AlGaAs/GaAs HETEROSTRUCTURES CONTAINING DEEP TRAPS

The results of calculations of the low-frequency and the high-frequency barrier capacitance of selectively doped AlGaAs/GaAs heterostructures containing deep traps in the AlGaAs layer are presented. The calculations are done for the samples in the dark and under extrinsic illumination. It is shown that the high-frequency photocapacitance of these structures exhibits a positive peak, and the low-frequency photocapacitance has a positive peak followed by a negative valley. The underlying physical mechanisms are discussed.