Light emitting nanostructures on the basis of (Al, Ga, In) N solid solutions with and without superlattices were investigated. Experiments in a wide range of temperatures (10-300 K) and currents (10 nA - 2 mA) were done. Comparison of structures with and without superlattices was performed. It was found that the structure with superlattices has higher stability and better work performance. Apparently, the use of superlattices can reduce an influence of elastic stresses and piezoelectric fields at the heterointerface. This may decrease the formation of dislocations, which increases the intensity of radiation and decreases self-heating effects.
Double heterostructure (DH) and quantum well (QW) EuSe/PbSe/Pb1−xEuxSe edge-emitting laser structures on Si substrates are grown by molecular-beam epitaxy. They operate up to 250 K when pumped with 870 nm low-cost laser diodes with peak powers of ∼7 W, and emit up to 200 mW peak output power at ∼5 μm wavelength. Differential quantum efficiencies are up to 20%. The threshold powers are limited by Shockley–Read recombination due to the high dislocation densities (108 cm−2) in the active layers. Nearly similar maximum operation temperatures were observed when employing (111)—instead of (100)—oriented layers, as well when using QW rather than DH structures. Reduction of dislocation densities to 107 cm−2 is feasible and will lead to nearly an order of magnitude lower threshold powers.
Two types of infrared emitters realised with IV-VI (lead chalcogenide) narrow-gap semiconductor materials on Si substrates are described. First, edge-emitting PbSe quantum well lasers with Pb1-xEuxSe claddings are grown on a BaF2 buffer layer on Si(100) substrates, removed from the substrate by dissolving the buffer layer and cleaved into resonator structures. Lasing around 4-5 mum wavelength is observed up to 240 K when illuminating with about 5 W-p from a 900 nm pump-laser-diode. Secondly, a resonant cavity PbSe/Pb1-xEuxSe structure on Si(111) with a one or two-pair BaF2/Pb1-yEuySe bottom mirror and a three-pair BaF2/EuSe top mirror exhibiting emission at e.g. 4.1 mum and 4% line-width, operates at room temperature and is tunable by design.
