Electroluminescent characteristics of InGaAsSb/GaAlAsSb heterostructure Mid-IR LEDs at high temperatures

The electroluminescent characteristics of an InGaAsSb/GaAlAsSb heterostructure LED emitting at 1.85 μm are studied in the temperature range 20–200°C. It is shown that the emission power exponentially drops as P ≅ 0.4exp(2.05 × 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 Δ E ≅ 32.9 − 0.075 T and the maximum of the LED’s emission spectrum shifts toward the long-wavelength range ( hν max = 0.693 − 4.497 × 10 −4 T ). Based on the dependence E g = hν max − 0.5 kT and experimental data, an expression is derived for the temperature variation of the bandgap in the In 0.055 Ga 0.945 AsSb active area, E g ≅ 0.817 − 4.951 × 10 −4 T , in the range 290 K < T < 495 K. The resistance of the heterostructure decreases exponentially with rising temperature as R 0 ≅ 5.52 × 10 −2 exp(0.672/2 kT ), while cutoff voltage U cut characterizing the barrier height of a p−n junction decreases linearly with increasing temperature ( U cut = −1.59 T + 534). It is found that the current through the heterostructure is due to the generation-recombination mechanism throughout the temperature interval.