An InP/GaInAs monolithic pin FET is fabricated using MOMBE crystal growth and Be ion implantation techniques. The MOMBE crystal growth technique is shown to be adaptable to the versatile requirements of the receiver crystal. The epigrowth together with the Be ion implantation provides a promising OEIC fabrication technique. The pin FET operated with 1.3 GHz bandwidth and 6 dB gain.