The gain characteristics of 1.3-mum-wavelength GaInNAs, InGaAlAs, and InGaAsP single-quantum-well structures are studied and compared. Among these quantum wells, GaInNAs offers the lowest carrier density over a wide range of temperature (300-400 K) for applications that require high gain because of the highest differential gain. It is due to the large electron effective mass originating from the nitrogen incorporation. The change in threshold carrier density with temperature is smallest for GaInNAs because of the large conduction band offset and the large differences in the band gap energy between the well and the barrier. The interaction with the temperature-independent nitrogen states makes the shift of gain with temperature slowest as well. For these reasons, the threshold current of GaInNAs is expected to be more temperature independent than those of other materials. (C) 2001 American Institute of Physics.