The effect of growth temperature on the crystal quality of Ga1-yInyNxAs1-x thin films by atomic hydrogen-assisted molecular beam epitaxy (H-MBE), and the characteristics of GaAs/Ga1-yInyNxAs1-x heterojunction solar cells were investigated. A high growth temperature of similar to 520 degrees C resulted in both an improved crystal quality and solar cell performance. The PL peak intensity measured for GaN0.003As0.997 film was three times higher than that for the sample grown at a more conventional growth temperature of 480 degrees C. Furthermore, the highest electron mobility of 250cm(2)/V s was obtained for the sample grown at 520 degrees C. An unoptimized p-GaAs/ i-n-GaInNAs heterojunction solar cell grown by H-MBE showed a maximum quantum efficiency of 50% and good diode factor of 1.4, respectively. (c) 2006 Elsevier B.V. All rights reserved.