A p -i-n semiconductor diode is used as the target for an electron-bombarded semiconductor amplifier. In such amplifiers, a form of evacuated electron tube has a conventional cathode, heater, and grid. However, the tube has the semiconductor diode target in place of the more conventional anode. A high beamaccelerating potential between the cathode and the target causes a high-velocity electron beam to bombard the target, which has its outer layer thin enough to permit the electrons to pass through to the intrinsic region of the diode, where the electrons generate electron-hole pairs. The semiconductor diode target is connected in series with an output load and a source of target bias potential that draws a current of the newly-created electron-hole pairs across the output load. The grid modulates the electron beam, which, in turn controls the current across the output load.