The SiH4 doping efficiency in InP and In0.54Ga0.46As/InP has been investigated for H-2 and the mixture N-2/H-2 (90%/10%) as carrier gases combined with the group-V precursors tertiarybutylarsine (TBA), tertiarybutylphosphine (TBP), PH3 or AsH3. The doping efficiency increases significantly with the use of TBA or TBP in either N-2/H-2 (90%/10%) or H2. The Si doping decreases with the use of N-2/H-2 (90%/10%) compared with H-2 which is attributed to the fact that the wafer surface temperature is approximately 25 degreesC lower when using N-2/H-2 (90%/10%) as the carrier whilst using the same growth temperature as recorded by thermocouples in the susceptor. For the growth of In0.53Ga0.47As in N-2/H-2 (90%/10%) the Si incorporation increases with the V/III ratio. Furthermore, the combination of TBA with N-2/H-2 (90%/10%) improves the resistivity uniformity.