A method for forming a solid state mass spectrograph for analyzing a sample gas is provided in which a plurality of cavities are formed in a substrate, preferably, a semiconductor. Each of these cavities forms a chamber into which a different component of the mass spectrograph is provided. A plurality of orifices are formed between each of the cavities, forming an interconnecting passageway between each of the chambers. A dielectric layer is provided inside the cavities to serve as a separator between the substrate and electrodes to be later deposited in the cavity. An ionizer is provided in one of the cavities and an ion detector is provided in another of the cavities. The formed substrate is provided in a circuit board which contains interfacing and controlling electronics for the mass spectrograph. Preferably, the substrate is formed in two halves and the chambers are formed in a corresponding arrangement in each of the substrate halves. The substrate halves are then bonded together after the components are provided therein.

Method for manufacturing a miniaturized solid state mass spectrograph

A gas ionizer is provided for use in a solid state mass spectrograph for analyzing a sample of gas. The gas ionizer is located in a cavity provided in a semiconductor substrate which includes an inlet for introducing the gas to be analyzed. The gas ionizer ionizes the sample of gas drawn into the cavity through the inlet to generate an ionized sample gas. The gas ionizer generates energetic particles or photons which bombard the gas to be sampled to produce ionized gas. The energetic particles or photons can be generated by reverse-bias p-n junctions, radioactive isotopes, electron discharges, point emitters, and thermionic electron emitters. A layer of cesium chloride or cesium iodide having a low work function is formed on top of the reverse-bias p-n junction gas ionizer to increase current emitted per junction area and so that the gas ionizer can be exposed to atmospheric oxygen during storage and can operate in reduced atmosphere with no additional treatments. The cesium chloride layer and the cesium iodide layer do not readily electromigrate. A fabrication process of the mass spectrograph includes using plural masks to ensure proper exposure of resist on both flat and wall surfaces of the semiconductor surface having severe topography.

Micro-miniature ionizer for gas sensor applications and method of making micro-miniature ionizer

An analysis is made of the changes occurring in the electrical characteristics of reverse-biased p-n junction electron emitters in SiC during the development of emission. The functional dependence of the emission on the junction voltage, current, mean cathode temperature and extraction field is investigated, and it is shown that the emission is directly proportional to the surface component of the junction current, which can be separated from the bulk current through the p-n junction. Emission is developed at points along the p-n junction by thermal processing, the magnitude of which determines the level of the emission, which is then stable at all lower values of power dissipation. The possibility of increasing the emission by pulsing the junction current is also examined.

https://iopscience.iop.org/article/10.1088/0022-3727/5/3/328/pdf

Some properties of reverse-biased silicon carbide p - n junction cold cathodes

Disclosed is a cascade voltage amplifier for producing an amplified output in pulse or continuous wave form comprises at least one non-final stage with an electron tube configured as a switching and Class A or C amplifying structure. A final stage comprises an electron tube configured as a Class A or C amplifying structure. The at least one non-final stage and the final stage are connected in series, and the amplified output has a voltage of at least 1000 volts. Further disclosed is a method of activating a plurality of cascaded electron tube stages within a common vacuum enclosure. Beneficially, a sufficient amount of energy supplied to the first stage serially propagates through any intervening stage to the final stage so as to facilitate activation of all tube stages.

Cascade voltage amplifier and method of activating cascaded electron tubes

The emission current from a reverse-biased p-n junction in SiC is known to be proportional to the surface component of the junction current, which in turn appears to be related to the junction voltage by a power law It is suggested that the surface current crosses the p-n junction not in surface microplasmas in the SiC but along paths in a thin surface film of silicon oxide heavily doped with carbon atoms from the SiC lattice It is postulated that, during the thermal activation required to develop emission, changes occur in the structure of the oxide film which facilitate the ionization of the carbon inclusions to give a high donor density in the region of the reverse bias field These ideas are shown to give a selfconsistent picture of the conduction and emission processes occurring in SiC cathodes and explanations of several observed phenomena are given

The predominant role of the surface films in the emission of electrons from reverse-biased p-n junctions in silicon carbide

A technique is described for fabricating a novel type of cold cathode comprising an array of electron emitters formed from a single p-n junction of silicon carbide. Two methods are described for developing emission from such a cathode, one of which involves running the cathode under reverse bias and the other heating under forward bias. The latter method appears more suitable for collectively activating a multi-emitter cathode, since it enables a high level of emission to be obtained in a relatively short time. The former method is slow and attempts to increase the rate of activation result in breakdown of the emitting elements. The effectiveness of these two methods has been assessed in terms of the emission and junction characteristics. Life tests show the activated cathode to be remarkably stable, although it is found to exhibit appreciable but reversible changes in emission level in the presence of certain contaminants.

https://iopscience.iop.org/article/10.1088/0022-3727/4/12/328/pdf

R V Bellau

Papers

Activation of a multi-emitter silicon carbide p-n junction cold cathode