Temperature dependence of luminescence was measured in InPxAs1−x:Yb crystals (x=7% and 12%) and in reference undoped material (x=8%). A simple correlation between Yb doping and the number of thermally activated bands in the near‐band‐edge spectral region of In(P,As) alloys was found. A new luminescence band located at ∼25 meV below the free‐carrier, band‐to‐band emission was observed in Yb‐doped alloys only. A one‐to‐one correspondence between the appearance of this band and the quenching of the intra‐4f‐shell photoluminescence of Yb3+ions is shown. These observations are taken as direct evidence for participation of excitons bound on Yb3+ion in the excitation and quenching processes of the 4fshell. ©1995 American Institute of Physics.