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Optics, Quantum Electronics
Electroluminescent characteristics of InGaAsSb/GaAlAsSb heterostructure Mid-IR LEDs at high temperatures
A. A. Petukhov,
B. E. Zhurtanov,
S. S. Molchanov,
N. D. Stoyanov,
Yu. P. Yakovlev Ioffe Institute, St. Petersburg
Abstract:
The electroluminescent characteristics of an InGaAsSb/GaAlAsSb heterostructure LED emitting at 1.85
$\mu$m are studied in the temperature range 20–200
$^\circ$C. It is shown that the emission power exponentially drops as
$P\cong$ 0.4
$\exp$(2.05
$\times$ 10
$^3$/T) with a rise in temperature primarily because of an increase in the Auger recombination rate. It is found that band-to-band radiative recombination goes in parallel with recombination through acceptor levels, the latter causing the emission spectrum to broaden. With a rise in temperature, the activation energy of the acceptor levels decreases by the law
$\Delta E\cong$ 32.9 – 0.075T and the maximum of the LED’s emission spectrum shifts toward the long-wavelength range (
$h\nu_{\mathrm{max}}$ = 0.693–4.497
$\times$ 10
$^{-4}$ T). Based on the dependence
$E_g=h\nu_{\mathrm{max}}-1/2 kT$ and experimental data, an expression is derived for the temperature variation of the bandgap in the Ga
$_{0.945}$In
$_{0.055}$AsSb active area,
$E_g\cong$ 0.817–4.951
$\times$ 10
$^{-4}$ T, in the range 290 K
$<T<$ 495 K. The resistance of the heterostructure decreases exponentially with rising temperature as
$R_0\cong$ 5.52
$\times$ 10
$^{-2} \exp$ (0.672/2
$kT$), while cutoff voltage
$U_{\mathrm{cut}}$ characterizing the barrier height of a
$p$–
$n$ junction decreases linearly with increasing temperature (
$U_{\mathrm{cut}}$ = -1.59T + 534). It is found that the current through the heterostructure is due to the generation-recombination mechanism throughout the temperature interval.
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