The principal design of a newly developed two-zone valved cracking phosphorus P 2 molecular beam source with greatly improved performance based on InP thermal decomposition is outlined. Precise dimer phosphorus beam flux control is accomplished due to a thoughtfully designed and externally activated faucet placed between the InP decomposition zone and the cracking area of P 4 vapors. Experimental tests show that the source can be easily incorporated into the standard ion-pumped molecular beam epitaxy (MBE) machine and can be used successfully for the MBE growth of device quality III-V single and multi-component phosphide epilayers incorporated into single-and multi-layer heterostructures with sharp interfaces.