N. M. Stus

Room temperature InAs photodiode–InGaAs LED pairs for methane detection in the mid-IR

Abstract InGaAs LEDs and InAs photodiodes with wide gap window were characterized at 0–80°C with respect to methane detection at 3.3–3.4 μm wavelengths. Signal-to-noise ratio as high as 4×10 3 and a limit of detection as low as 170 ppm have been estimated for a single LED pulse of I =3 A, τ =10 μs at room temperature.

Towards efficient mid-IR LED operation: optical pumping, extraction or injection of carriers?

Positive and negative output power, spectral and current—voltage characteristics of the In(Ga)As and InAs(Sb) based heterostructure light-emitting diodes with the ‘episide-down’ construction grown onto heavily doped n+-InAs have been examined in the 20-200°C temperature range. Optically pumped LEDs composed from the above heterostructures or from InSb exhibited output characteristics fairly close to the conventional LEDs. Wavelength and temperature variation of the emission power in the 3.3–8 μm spectral range was compared with the phenomenological model based on the expectations of the negative luminescence power (NLP) and saturation current (I sat). The crossover of forward bias power at 1 A and negative power at I = I sat takes place at 90 and 160°C for 5.3 and 4.3 μm LEDs correspondingly.

Sources of spontaneous emission based on indium arsenide

The results obtained for light-emitting diodes based on heterostructures that contain InAs in the active region and are grown by the methods of liquid-phase, molecular-beam, and vapor-phase epitaxy from organometallic compounds are reviewed. The emission intensity, the near-field patterns, and the light-current and current-voltage characteristics of light-emitting diodes that have flip-chip structure or feature a point contact are analyzed.

Room-temperature broadband InAsSb flip-chip photodiodes with λcut off = 4.5 μm

Equilibrium and nonequilibrium IR images of p-InAsSbP/n-InAsSb/n+-InAs photodiodes including the images obtained in the electroluminescence and negative luminescence modes have been analyzed. The contact reflectivity has been evaluated. The influence of the substrate’s doping level and mesa depth on the quantum efficiency and sensitivity of a backside illuminated photodiode sensitive in the 2.7–4.5 μm range is discussed.

Flip-chip LEDs with deep mesa emitting at 4.2 µm

The spectral, current-voltage, and emission-current characteristics under forward and reverse biases, and the near-field emission pattern of flip-chip LEDs based on heterostructures with an InAsSb active layer (emission wavelength of 4.2 µm at 300 K) and a mesa of 40–50 µm in depth and 240 µm in diameter are analyzed. The possibility of raising the emission output by varying the configuration of the structure and selecting the optimal operation mode dependently on the working temperature are discussed.

Gadolinium-doped InGaAsSb solid solutions on an InAs substrate for light-emitting diodes operating in the spectral interval λ=3–5 µm

The influence of a gadolinium impurity on the electrical and luminescence characteristics of epitaxial structures made from narrow-gap n-InGaAsSb solid solutions grown by liquid-phase epitaxy on InAs substrates is investigated. The addition of gadolinium to the flux solution in the interval of concentrations 0<XGdl⩽0.14 at. % has the effect of lowering the density of electrons in the InGaAsSb layers from (3–6)×1016 cm−3 to (7–8)×1015 cm−3 and increasing the carrier mobility from 32 000 cm2/(V·s) to 61 500 cm2/(V·s) (T=77 K). Also observed are a decrease in the half-width of the photoluminescence spectra from 25 meV to 12 meV and as much as a tenfold increase in their intensity (T=77 K). The electroluminescence intensity of LEDs fabricated from gadolinium-doped n-InGaAsSb/p-InAs epitaxial structures (T=300 K) increases approximately a factor of 2 relative to the undoped samples.

Negative luminescence in p-InAsSbP/n-InAs diodes

Negative luminescence (NL) at λmax=3.8 µm from reverse-biased p-InAsSbP/n-InAs diode heterostructures has been studied at temperatures of 70–180°C. The NL power increases with temperature and exceeds the power of direct-bias electroluminescence at temperatures over 110°C. An NL power of 5 mW/cm2, efficiency of 60%, and a conversion efficiency of 25 mW/(A cm2) have been obtained at 160°C.

Spatial redistribution of radiation in flip-chip photodiodes based on InAsSbP/InAs double heterostructures

The spatial distribution of equilibrium and nonequilibrium (including luminescent) IR (infrared) radiation in flip-chip photodiodes based on InAsSbP/InAs double heterostructures (λmax = 3.4 μm) is measured and analyzed; the structural features of the photodiodes, including the reflective properties of the ohmic contacts, are taken into account. Optical area enhancement due to multiple internal reflection in photodiodes with different geometric characteristics is estimated.

Spatial nonuniformity of current flow and its consideration in determination of characteristics of surface illuminated InAsSbP/InAs-based photodiodes

Current-voltage characteristics of surface-irradiated photodiodes based on the InAsSbP/InAs structures are analyzed using experimental data on the distribution of electroluminescence intensity over the diode surface and taking into account thickening the current streamlines near the contacts. The influence of the potential barrier associated with the N-InAsSbP/n-InAs junction in double heterostructures on the differential resistance of diodes under zero bias, the value of the reverse current, and spreading of the forward current is discussed.

Light emitting diodes for the spectral range λ=3.3–4.3 µm fabricated from InGaAs and InAsSbP solid solutions: Electroluminescence in the temperature range of 20–180°C (Part 2)

Light-emitting diodes (LEDs) based on p-n homo-and heterostructures with InAsSb(P) and InGaAs active layers have been designed and studied. An emission power of 0.2 (λ=4.3 µm) to 1.33 mW (λ=3.3 µm) and a conversion efficiency of 30 (InAsSbP, λ=4.3 µm) to 340 mW/(A cm2) (InAsSb/InAsSbP double heterostructure (DH), λ=4.0 µm) have been achieved. The conversion efficiency decreases with increasing current, mainly owing to the Joule heating of the p-n homojunctions. In DH LEDs, the fact that the output power tends to a constant value with increasing current is not associated with active region heating. On raising the temperature from 20 to 180°C, the emission power of the (λ=3.3 and 4.3 µm) LEDs decreases, respectively, 7-and 14-fold, to become 50 (at 1.5 A) and 7 µW (at 3 A) at 180°C.