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(a) PL spectra of the 0% Bi InGaAs/InP sample at 200 mW laser power at different temperatures. Spectra are normalised to the same peak height (295 K spectrum is ∼28 times weaker than at 30 K). (b) PL spectra of InGaBiAs/InP samples with 1.1% (solid curves) and 2.4% Bi (dashed curves) at various laser powers and temperatures: 1.1% Bi—50 mW (at 30, 60, 90, and 120 K), 200 mW (160, 190, and 220 K), 300 mW (250 and 290 K), 500 mW and 1 W (both at 290 K); 2.4% Bi—200 mW (30 and 90 K) and 2 W (250 K).
Example PR spectra of (a) the 1.1% and (b) the 2.4% Bi-containing samples at various temperatures in region of Eg. Open circles indicate fitted transition energy of lowest-energy feature (see also Fig. 3). Feature near 0.73 eV at 296 K is due to In0.53Ga0.47As buffer layer.
PR spectrum (symbols) with fitting curves (solid curves), squared absorption coefficient spectrum (dashed curve with linear fit to determine Eg), and PL spectrum at 295 K for InGaBiAs/InP sample with 1.1% Bi. Arrows indicate bandgap determined by each technique. Inset plots absorption coefficient on logarithmic scale.
Measured bandgap, Eg, and spin-orbit splitting, ΔSO, from room temperature absorption, PL and PR spectra (symbols). Curves show VBAC calculations for InGaBiAs for different In compositions from 0% to 53%, versus Bi fraction.
(a) Temperature dependence of PL and PR Eg values for 0, 1.1, and 2.4% Bi. Solid curve is Varshni fit of PL Eg of 0% Bi sample with parameters: α = 0.50 meV/K, β = 327 K, E0 = 0.787 eV. Dashed lines are linear fits of Eg(T) from 150 to 300 K, numbers near each line giving gradients, dEg/dT (meV/K). Lower dashed-dotted curves show extrapolated long wavelength PL peak energies, using same Varshni fit as for 0% Bi bandgap.
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