Abstract
There is continuing interest in the development of superlattices for use in photonic devices operating in the technologically important mid-infrared spectral range. In this work type-II strained-layer superlattices of InAs/InAs1-xSbx (x = 0.04 and x = 0.06) were grown on InAs (1 0 0) substrates by MBE. Structural analysis of the samples revealed good crystalline quality but a non-uniform distribution of Sb within the QWs which originated from segregation effects during growth. Bright photoluminescence emission was obtained at low temperature (4 K) which persisted up to 300 K. Two prototype samples were grown containing the corresponding superlattices in the active region and fabricated into LEDs. Mid-infrared electroluminescence was obtained from both these LEDs over the temperature range 7–300 K and both devices exhibit emission coincident with the main CO2 absorption band near 4.2 μm at room temperature. These LEDs produced output powers of 8.2 µW and 3.3 µW under 100 mA injection current at room temperature and are of interest for CO2 detection and further development for mid-infrared gas sensing applications.
Highlights
Light-emitting diodes (LEDs) operating in the technologically important mid-infrared spectral range are highly desirable as key components in instrumentation for a variety of applications, including the sensing and monitoring of environmentally harmful gases, [1, 2, 3], medical diagnostics and treatments [4, 5], space technology [6] and security and defence [7, 8]
A few threading dislocations are observed at the substrate – strained-layer superlattice (SLS) interface, and a small number of misfit dislocations can be seen inside the SLS, Transmission electron microscope (TEM) images taken in different places show defect free regions
Two p-n0-n diode samples were grown containing the corresponding superlattices in the active region and fabricated into LEDs
Summary
Light-emitting diodes (LEDs) operating in the technologically important mid-infrared spectral range are highly desirable as key components in instrumentation for a variety of applications, including the sensing and monitoring of environmentally harmful gases, [1, 2, 3], medical diagnostics and treatments [4, 5], space technology [6] and security and defence [7, 8]. Electroluminescence emission spectra from the two SLS LEDs at temperatures in the range 7 – 300 K, driven using a constant 100 mA quasi-continuous (qCW) excitation at 1 kHz, are shown, alongside the 4 – 300 K photoluminescence spectra of the corresponding samples as reported in our previous work [23].
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