A process and system for making semiconductor alloys and members with high reaction gas conversion efficiencies and at high deposition rates utilizes microwave energy to form a deposition plasma. The microwave energy forms depositing species and molecular ions of a semiconductor elememt and the potential of the plasma is controlled to alter the ion bombardment of the depositing species. The process and system include coupling microwave energy into a substantially enclosed reaction vessel (12) containing a substrate (14) and depositing semiconductor alloys onto the substrate from a reaction gas introduced into the vessel. The semiconductor alloys are particularly suited for relatively thick photoconductive members 40,50,62,72). The photoconductive member includes at least a bottom blocking layer (44, 54, 66, 76) and a photoconductive layer (46, 56, 68, 78). The photoconductive member can be formed in a negative (62, 72) or positive (40, 50) charge type configuration. The members also can include a top blocking enhancement layer (60,82).