Rapid tuning of the generation frequency of InAsSb/InAsSbP diode lasers (λ=3.3 µm) due to nonlinear optical effects

A study has been made of wavelength tuning in double heterostructure InAsSb/InAsSbP-based diode lasers. A simple mathematical model, which takes into account the spatially homogeneous injection and the dependence of the dielectric constant on the charge carrier density, is discussed. The wavelength can be increased or decreased, depending on the pump current and diode structure parameters, as is observed experimentally. The process of wavelength tuning proceeds with virtually zero delay time since it is determined by the photon lifetime in the cavity and in part by the lifetime of nonequilibrium charge carriers. Fiz. Tekh. Poluprovodn. 33, 243–248 (February 1999)     

Two-mode diode-laser spectroscopy with a InAsSb/InAsSbP laser near 3.6 µm

The current dependence of the output frequency of InAsSb/InAsSbP diode lasers at wavelengths near 3.6 μm is studied. It is found that in these lasers the number of lasing modes can be reduced without introducing crystallographic defects. It is shown that the photon momentum aids in suppressing the spectral modes closest to the dominant mode. Two-mode laser spectroscopy is done over an interval of 2 cm⁻¹ for two gases, N₂O and CH₃Cl. Fiz. Tekh. Poluprovodn. 33, 1469–1474 (December 1999)     

Ultrafast frequency tuning in diode lasers based on InAsSb/InAsSbP heterostructures operating in the 3–4 μm spectral range

We have studied the quality of frequency of tuning in a diode laser based on a double heterostructures of the n-InAsSbP/n-InAsSb/p-InAsSbP type driven by short current pulses with positive ramp top. It is established that a monotonic increase in the tuned mode frequency with the time is retained during the first 30-μs-long period of current growth. Then, the dependence of the frequency on the current weakens because of the appearance of nontunable modes. The maximum range of monotonic single-frequency tuning is achieved at a small pulse duration (< 30 μs), which shows prospects for the development of ultrafast-response laser diode spectroscopy.     

Temperature dependence of the threshold current in quantum-well WGM lasers (2.0–2.5 μm)

The temperature dependence of the threshold current and emission spectra of disk-shaped quantum-well whispering-gallery mode (WGM) lasers is studied in the temperature range of 80–463 K in which the laser emission wavelength increases from 2 to 2.5 μm. It is shown that lasing is observed up to 190°C. Radiative recombination is dominant up to a temperature of 300 K, and nonradiative Auger recombination, in which a recombining electron gives energy to another electron, is so at higher temperatures. The spin-orbit split-off valence subband is not involved in recombination processes, which is attributed to mechanical compression of the quantum-well material.     

Study of the emission extraction efficiency of mesa-LEDs with a narrow-gap InAsSb active region

A series of light-emitting diodes (LEDs) (emission peak wavelength λ_max = 3.6 μm) with cone-shaped mesas, which have concave lateral surfaces and heights between 10 to 130 μm, has been developed. The dependence of the emission efficiency for these LEDs on mesa height has been studied at different injection currents at the temperatures 77 and 298 K. The form of the dependence observed is in agreement with the results of theoretical calculations. It is shown that the effective absorption coefficient, caused by emission extraction from the crystal, may be as large as 3 cm⁻¹ for LEDs with the highest mesa (130 μm) among the diodes in this series. The emission extraction coefficient is close to 30% at the temperature 298 K and 94% at 77 K.     

Infrared light-emitting diodes based on GaInAsSb solid solutions grown from lead-containing solution-melts

Light-emitting diodes (LEDs) were fabricated on the basis of GaInAsSb alloys grown from lead-containing solution-melts. Electroluminescence characteristics and their current and temperature dependences were studied. The external photon yield at room temperature was 1.6 and 0.11% for LEDs with emission wavelengths λ=2.3 and 2.44 μm, respectively. For LEDs with emission wavelength λ=2.3 μm, the average emission power P=0.94 mW was attained in the quasi-continuous mode at room temperature. In the pulsed mode, the peak radiation power was P=126 mW at a current of 3 A, a pulse duration of 0.125 μs, and a frequency of 512 Hz. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 38, No. 12, 2004, pp. 1466–1472. Original Russian Text Copyright ? 2004 by Astakhova, Grebenshchikova, Ivanov, Imenkov, Kunitsyna, Parkhomenko, Yakovlev.     

Photovoltage and photocurrent in Pd–oxide–InP structures in a hydrogen medium

Pd–oxide–InP (MOS) structures are fabricated, and their physical and photoelectric properties in a hydrogen atmosphere are investigated. It is established that a decrease in photovoltage of the structure and a large increase in photocurrent in the circuit are observed under the pulsed effect of hydrogen on the structure with a palladium layer illuminated by a light-emitting diode (LED of the wavelength λ = 0.9 μm). The kinetics and mechanism of the variation in the photovoltage and photocurrent are considered. It is assumed that the photovoltage decreases because of the ionization of hydrogen atoms in the Pd layer, and the photocurrent increases due to the thermionic emission of nonequilibrium electrons from the Pd layer into the semiconductor. On the basis of results of the investigations, the sensitive element for an optoelectronic hydrogen sensor is developed.     

Improving parameters of GaSb/GaInAsSb/AlGaAsSb photodiode structures with thin active regions for the 1.0–2.5 μm wavelength range

We have studied and optimized the properties of photodiodes with a red photosensitivity threshold at 2.5 μm, which have been created on the basis of GaSb/GaInAsSb/AlGaAsSb heterostructures with Ga_0.76In_0.24As_0.22Sb_0.78 active regions of variable thickness and a reflecting contact on the rear side. It is established that a decrease in the thickness of the active region and the reflection of radiation from the rear side lead to an improvement in the parameters of photodiodes and related thermophotovoltaic converters in the 1.0–2.5 μm wavelength range. The optimized structures showed a detection ability of D*_λ = (3–6) × 10¹⁰ cm Hz^1/2/W and an open-circuit photo emf up to V _oc = 0.2 V.     

Impact-ionization-stimulated electroluminescence in isotype <Emphasis Type="Italic">n</Emphasis>-GaSb/<Emphasis Type="Italic">n</Emphasis>-AlGaAsSb/<Emphasis Type="Italic">n</Emphasis>-GaInAsSb heterostructures

We have studied electroluminescence in n-GaSb/n-AlGaAsSb/n-GaInAsSb heterostructures with isotype heterojunctions, in which the quantum efficiency of emission is increased due to the additional production of electron-hole pairs as a result of the impact ionization that takes place near the heterointerface. The impact ionization in such heterostructures is possible due to the presence of deep wells in the energy band structure.     

Spatial distribution of the radiation in the far zone of InAsSb/InAsSbP mesastrip lasers as a function of current

The far-zone directional pattern of diode mesastrip lasers with a 10 μm wide strip has been investigated as a function of the current. The directional pattern in the plane of the p-n junction contains one longitudinal mode, whose width depends on the current. It is shown by comparing the theoretically computed and experimentally measured spatial modes that this dependence is determined by the variation of the light flux intensity and the free-carrier density distributions over the strip width as a function of the current. In the case when the distributions are close to uniform the maximum narrow spatial longitudinal mode and a unimodal radiation spectrum are observed. Fiz. Tekh. Poluprovodn. 32, 373–376 (March 1998)