A solid state mass spectrograph includes an inlet, a gas ionizer, a mass filter and a detector array all formed within a cavity in a semiconductor substrate. The gas ionizer can be a solid state electron emitter with ion optics provided by electrodes formed on apertured partitions in the cavity forming compartments through which the cavity is evacuated by differential pumping. The mass filter is preferably a Wien filter with the magnetic field provided by a permanent magnet outside the substrate or by magnetic film on the cavity walls. The electric field of the Wien filter is provided by electrodes formed on walls of the cavity. The detector array is a linear array oriented in the dispersion plane of the mass filter and includes converging electrodes at the end of the cavity serving as Faraday cages which pass charge to signal generators such as charge coupled devices formed in the substrate but removed from the cavity.