Superlinear Luminescence and Enhancement of Optical Power in GaSb-based Heterostructures with High Conduction-Band Offsets and Nanostructures with Deep Quantum Wells
Maya P. Mikhailova; Leonid V. Danilov; Karina V. Kalinina; Edward V. Ivanov; Nikolay D. Stoyanov; Georgy G. Zegrya; Yury P. Yakovlev; Alice Hospodkova; Jiri Pangrac; Marketa Zikova; Eduard Hulicius
DOI: 10.1117/3.1002245.ch5
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Excerpt

Heterostructures and nanostructures with quantum wells (QWs) based on the GaSb/InAs/AlSb system are promising for developing optoelectronic devices (light-emitting diodes, lasers, photodetectors) because they cover the mid-infrared spectral range (1.6-5.0 μm), where absorption bands of many natural and industrial gases and other substances exist (CO2, CO, CH4, H2O, H2S, NH3, and many others). However, the optical power and quantum efficiency of light-emitting diodes (LEDs) based on the narrow-gap semiconductor alloys (InAsSb, InGaAsSb) are not sufficiently high and are limited by nonradiative Auger recombination. It was shown that Auger recombination can be suppressed at the type-II abrupt heterointerface and in nanostructures with deep QWs.

A system of InGaAsSb/GaSb alloys is also of interest due to the fact that, by varying the composition of the layers, one can obtain type-II heterojunctions with both staggered and broken-gap alignment. A specific feature of type-II heterojunctions is that self-aligned QWs on both sides of the boundary in which charge carriers are localized maintain the electrons and holes spatially separated. In such structures it is possible to obtain emission at longer wavelengths because of tunneling transitions of charge carriers through the heteroboundary. Due to the interaction of carriers with the heteroboundary in type-II heterostructures, the Auger recombination process is thresholdless, since the conservation law for the momentum component perpendicular to the heteroboundary is not fulfilled. In this case, the Auger recombination rate is a power function of temperature.

The possibility of creating a laser for the mid-infrared spectral range based on a semiconductor heterostructure with deep AlSb/InAs0.84Sb0.16 QWs was theoretically studied, and parameters of such a QW where nonradiative Auger recombination can be essentially suppressed were defined. Earlier it was proposed to use large conduction-band offsets ΔEC (or ΔEV) in an abrupt heterointerface with a narrow-gap active region for creation of hot electrons that can cause impact ionization beginning from their zero kinetic energy. An increase in the quantum yield of the internal photoeffect in InSb due to impact ionization by high-energy photons was considered for the first time by Tauc and Abrahám. Capasso et al. proposed the use of a large conduction-band offset at the heterointerface in order to raise the electron ionization coefficient in comparison with the hole ionization coefficient in a GaAs/AlGaAs superlattice avalanche photodiode (APD) (both ionization coefficients can be approximately the same in bulk material). However, this approach has not yet been applied to light-emitting devices.

Thus, it is important to find a way to increase the quantum efficiency and optical power of light-emitting devices based on narrow-gap semiconductors. In this work we report on the results of the electroluminescence (EL) study and enhancement of optical power in mid-infrared LEDs based on type-II heterostructures with high conduction-band offsets at the interface and in nanostructures with deep QWs by using the effect of impact ionization.

© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)

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