Продемонстрирована возможность формирования гибридных метаморфных гетероструктур вертикально излучающих лазеров (ВИЛ) спектрального диапазона 1300 нм. Метаморфная полупроводниковая часть гетероструктуры с распределенным брэгговским отражателем на основе пары GaAs/AlGaAs и активной областью на основе квантовых ям InAlGaAs/InGaAs выращена методом молекулярно-пучковой эпитаксии на подложке GaAs(100). Верхнее диэлектрическое зеркало с распределенным брэгговским отражателем сформировано на основе пары SiO2/Ta2O5 методом магнетронного распыления. Проведено изучение спектров микрофотолюминесценции гетероструктур вертикально излучающих лазеров при комнатной температуре в диапазоне мощностей 0-70 мВт (длина волны оптической накачки составила 532 нм, диаметр сфокусированного пучка ~ 1 мкм). Наличие сверхлинейного хода зависимости интенсивности фотолюминесценции от мощности накачки наряду с заужением полуширины пиков фотолюминесценции и изменением модового состава могут быть обусловлены лазерной генерацией гетероструктуры вертикально излучающих лазеров. Полученные результаты свидетельствуют о возможности использования технологии метаморфного роста гетероструктур на подложках GaAs для создания вертикально излучающих лазеров спектрального диапазона 1300 нм. DOI: 10.21883/FTP.2017.09.44879.8557

The results of studying the optical properties of InGaAs quantum dots are presented. Single-layer InGaAs quantum dots with a height of 5.3, 3.6 and 2.6 monolayers, as well as three-stacked layers of tunnel-uncoupled quantum dots with a height of 2.6 monolayers were formed by molecular–beam epitaxy according to the Stransky-Krastanov mechanism on GaAs substrates, using the partial capping and annealing technique. A decrease in the size of quantum dots makes it possible to carry out a blueshift of the photoluminescence spectrum maximum from 1200 nm to 1090 nm, and an increase in the number of QD layers makes it possible to compensate for the decrease in the peak intensity. It is shown that this type of quantum dots is suitable for creating the lasers active regions with a vertical microcavity for neuromorphic computing.

The static and dynamic characteristics of waveguide photodetectors with an absorbing region based on InGaAs/GaAs quantum well-dots were studied at room temperature. The absorption band of InGaAs/GaAs quantum well-dots is in the spectral range from 900 to 1100 nm. The waveguide photodetectors have a width of 50 µm and a length of the absorbing region from 92 µm to 400 µm. A low dark current density (1.1 и 22 μA/cm^2 at -1 и -20 V) and cut off frequency of 5.6 GHz, limited by the time constant of a parasitic equivalent electric RC circuit, were obtained.

Microdisk lasers 10–30 μm in diameter operating at room temperature without thermal stabilization and with an active region based on nanostructures of hybrid dimensionality—quantum wells–dots—are investigated. High-frequency measurements of the microlaser response are performed in the direct small-signal modulation mode, which makes it possible to establish the parameters of the operating speed and analyze their dependence on the microlaser diameter. It is found that the K factor is (0.8 ± 0.2) ns, which corresponds to optical losses of ~6 cm^–1, and no regular dependence on the diameter is observed. It is found that the low-frequency component of the damping coefficient of relaxation oscillations is inversely proportional to the diameter. This character of the dependence evidences a decrease in the carrier lifetime in small-diameter microcavities, which can be associated with the prevalence of nonradiative recombination on their side walls.

The paper presents the results of experiments in the fabrication and research of properties of photodetector structures on the basis of monolayer graphene produced by chemical vapor deposition. The base structure was the geometry of a Ta2O5 vertical microcavity with a lower dielectric SiO2/Ta2O5 distributed Bragg reflector with a resonance wavelength of about 850 nm. The conditions were optimized for the transfer and fabrication of mesas in the graphene layer on the microcavity surface. The diagnostics of the structural quality of graphene after the fabrication of mesas in the graphene layer and contact pads by Raman spectroscopy evidence the monolayer structure of graphene with a low singularity strength in its spectrum that is responsible for the structure imperfection. The photocurrent value at local optical pumping was measured.