An electron source is formed on a silicon substrate having opposing first and second surfaces. At least one field emitter is prepared on the second surface of the silicon substrate to enhance the emission of electrons. To prevent oxidation of the silicon, a thin, contiguous boron layer is disposed directly on the output surface of the field emitter using a process that minimizes oxidation and defects. The field emitter can take various shapes such as pyramids and rounded whiskers. One or several optional gate layers may be placed at or slightly lower than the height of the field emitter tip in order to achieve fast and accurate control of the emission current and high emission currents. The field emitter can be p-type doped and configured to operate in a reverse bias mode or the field emitter can be n-type doped.