Thermally cracked tertiarybutylarsine and tertiarybutylphosphine were used to replace AsH3and PH3for the growth of Ga0.47In0.53As and InP by metalorganic molecular beam epitaxy. For both materials, carrier concentrationsn=(1–2)×1015cm−3were obtained at 300 and 77 K, with 77 K mobilities of 29 000 and 31 000 cm2 V−1 s−1. The GaAs wasp‐type withp=4×1015cm−3at both temperatures and a 77 K mobility of 2200 cm2 V−1 s−1. The lifetimes for carriers in 14–60 A˚ thick quantum wells were 3±1 ns. The reacting arsenic species for epitaxy were As2and As4. The reacting phosphorus species were PH2and possibly PH.