A single-mask structure for a micrometer-sized silicon triode (microtriode) is proposed. The fabrication of the device has been optimized to produce a suspended chromium gate above a pyramidal silicon cathode. The gate approaches from the side, in the same plane as the anode. Field emission between the anode and cathode in diode-mode operation in atmosphere has been confirmed. Diode-mode operation of the device is suitable for sensor applications.