Carbon doped AlInAs layers grown by low pressure metalorganic vapor phase epitaxy are investigated as a function of growth temperature. Photoluminescence spectra show a significant drop in peak intensity as the growth temperature is reduced, due to the incorporation of non-radiative defects. It is shown that the C doping is not related to the deterioration of the optical properties of the layers. On the other hand, both the net hole concentration and the conductivity increase as the growth temperature is reduced due to a more efficient C incorporation and a lower incorporation of the passivating H atoms.