InGaN-based ultraviolet emitting heterostructures with quaternary AlInGaN barriers

Nitride-based ultraviolet (UV) heterostructures with InGaN quantum wells and AlInGaN barrier layers have been grown by metal-organic chemical vapor deposition on sapphire substrates. The emission band was at 3.307 eV (375 nm) at room temperature (RT) and its full-width at half-maximum was ∼82meV. In addition to the UV band, some blue emission admixture was found in a single-quantum-well (SQW) structure, which the authors attribute to recombination of injected electrons that are not captured into the SQW and enter the p-side of the structure. The authors demonstrate a significant advantage in utilizing multiple-quantum-well (MQW) structures that provide a more effective capture of injected carriers into wells and predominance of UV emission. Temperature-sensitive competition between two emission mechanisms in MQW structures has been observed. Below ∼170 K, the blue impurity-related emission dominated. In the 170-190 K range, an anomalous temperature-induced "blue jump" by over ∼340 meV to UV region occurred, with UV emission dominating above 190 K.