InGaAs layers were grown on InP substrates by MOCVD using CBr4 sources and 3×1019 cm-3 doping was achieved upon annealing and de-passivation from hydrogen. The impact of annealing was investigated by FTIR, SIMS and Hall measurements. The results show the presence of the H-(CAs)2 complex and a loss of hydrogen upon annealing which is estimated to be ∼33% by FTIR and ∼50% by SIMS. These results are consistent considering the fact that FTIR refers only to C-H bonds. In and As variations near the surface and some carbon concentration variation upon annealing is also reported.