Nitrogen addition promises temperature-stable near-infrared diode lasers

Nitrogen addition promises temperature-stable near-infrared diode lasers

Researchers H. P. Xin and C. W. Tu of the University of California, San Diego (La Jolla, CA), have grown multiple quantum wells (QWs) from gallium indium nitrogen arsenide/gallium arsenide (GaInNAs/GaAs) with a photoluminescence (PL) peak at 1.3 µm. These QWs may pave the way for a new family of infrared diode lasers. Conventional gallium indium arsenide phosphide/indium phosphide (GaInAsP/InP) lasers for communications have undesirable temperature characteristics, which the nitrogen-bearing materials avoid. Room-temperature PL peaks of at least 1.3 µm are required for optical communications applications. The researchers grew seven-period QWs from alternating GaInNAs and GaAs layers on a GaAs substrate. Different nitrogen compositions were grown on semi-insulating GaAs substrates by gas-source molecular-beam epitaxy.

Adding nitrogen stabilizes the temperature performance of the material, but it also causes other changes. As nitrogen concentrations increase, the compressive strain on the material is reduced (because the atomic size of nitrogen is about 7.5 nm versus 12 nm for arsenic), the bandga¥is reduced, the PL peak intensity decreases, and the peak width of the PL increases. These results are useful for developing longer-wavelength lasers from GaInNAs/GaAs.