Epitaxial layers containing phosphorus (P) find numerous applications in electronic and photonic devices such as GaInP/GaAs HBTs, InAlAs/InGaAs/InP double HBTs, GaP LEDs and InP/InGaAsP MQW lasers operating at 1.3-1.55 /spl mu/m. These structures have been realized traditionally either by MOCVD, GSMBE or CBE relying on highly toxic hydrides as the gas sources for phosphorus and arsenic. Solid-source MBE provides the simplest and most elegant solution for growing complex epitaxial structures; however, the unique physical properties of solid phosphorus make it difficult to grow P-containing layers. By using a recently developed phosphorus valved cracker, excellent InP heterostructures have been achieved. We have explored the use of InP active layers in InP-based HBT grown entirely by solid-source MBE and compared them to InAlAs/InGaAs HBTs.