Abstract A solid state radiation sensitive field emitter cathode comprising a single crystal semiconductor member having a body portion with a uniform array of closely spaced and very sharp electron emitting projections from one surface in the form of needles or whisker like members. Electrons are emitted into vacuum when a planar-parallel positive anode is mounted in close proximity to the surface. The cathode is responsive to input radiation such as electrons or light directed onto the cathode in modifying the electron emission from the array of electron emitter projections. The method of manufacturing the cathode by providing a predetermined pattern or mosaic of islands of a material exhibiting a greater etch resistant property than the semiconductor material, on a wafer of a semiconductor material and then etching out between and beneath the islands to undercut to a point where the islands are supported by only a small whisker of the semiconductor material. Removal of the islands results in an electron emitter being exposed from beneath each island wherein carriers generated within the body portion and also carriers generated within the depletion regions of the tips deffuse to the electron emitter projections wherein establishment of a high electric field at the tips of the electron emitter projections results in electron emission primarily due to conduction band tunneling. The device provides about 106 emitting points of close proximity so as to effect photographic-like imaging.
THE METHOD OF FABRICATING A LARGE AREA FIELD ELECTRON EMITTER DEVICE COMPRISING THE STEPS OF PROVIDING A WAFER OF A SEMICONDUCTIVE MATERIAL OF A SINGLE CRYSTAL MATERIAL AND HAVING A BAND GAP IN THE RANGE OF 0.2 TO 3.0 ELECTRON VOLTS AND A RESISTIVITY OF 0.10 OHM CENTIMETER OR GREATER, DEPOSITING AN ETCH-RESISTANT ARRAY PATTERN OF ISLANDS OVER SAID WAFER ON ONE SURFACE THEREOF, ETCHING SAID SEMICONDUCTIVE WAFER IN A MANNER TO REMOVE A PORTION OF THE SEMICONDUCTIVE MATERIAL FROM BENEATH AND BETWEEN THE ISLANDS OF SAID ARRAY TO PROVIDE A CENTRALLY LOCATED SUPPORT PROJECTION FOR EACH OF SAID ISLANDS HAVING A DIAMETER OF ABOUT 1.5 MICRONS AT THE UPPER POINT OF SAID SUPPORT ADJACENT SAID ISLAND, GROWING AN OXIDE LAYER ON SAID ETCHED OUT SURFACE OF SAID WAFER TO PROVIDE AN OXIDE COATING HAVING A THICKNESS OF ABOUT 0.5 MICRONS AND PROVIDING A REMAINING CENTRAL REGION OF SEMICONDUCTIVE MATERIAL AT THE POINT SUPPORTING SAID ISLAND OF ABOUT 0.5 MICRONS, REMOVING SAID RESIST ARRAY TO PROVIDE A LARGE AREA OF FIELD EMITTERS COMPRISED OF A SUBSTRATE OF SEMICONDUCTIVE MATERIAL WITH A PLURALITY OF PROJECTING ELECTRON EMITTERS EXTENDING FROM SAID SUBSTRATE IN A CRYSTALLOGRAPHICALLY CONTINUOUS MANNER IN WHICH SAID PROJECTING ELECTRON EMITTERS COMPRISE AN EMITTING POINT HAVING A DIAMETER OF ABOUT 0.5 MICRONS.
Claim 2
Independent Claim
212 words
THE METHOD OF FABRICATING A LARGE AREA FIELD ELECTRON EMITTER DEVICE COMPRISING THE STEPS OF PROVIDING A WAFER OF A SEMICONDUCTIVE MATERIAL OF A SINGLE CRYSTAL MATERIAL AND HAVING A BAND GAP IN THE RANGE OF 0.2 TO 3.0 ELECTRON VOLTS AND A RESISTIVITY OF 0.10 OHM CENTIMETER OR GREATER, DEPOSITING AN ETCH-RESISTANT ARRAY PATTERN OF ISLANDS OVER SAID WAFER ON ONE SURFACE THEREOF, ETCHING SAID SEMICONDUCTIVE WAFER IN A MANNER TO REMOVE A PORTION OF THE SEMICONDUCTIVE MATERIAL FROM BENEATH AND BETWEEN THE ISLANDS OF SAID ARRAY TO PROVIDE A CENTRALLY LOCATED SUPPORT PROJECTION FOR EACH OF SAID ISLANDS HAVING A DIAMETER OF ABOUT 1.5 MICRONS AT THE UPPER POINT OF SAID SUPPORT ADJACENT SAID ISLAND, GROWING AN OXIDE LAYER ON SAID ETCHED OUT SURFACE OF SAID WAFER TO PROVIDE AN OXIDE COATING HAVING A THICKNESS OF ABOUT 0.5 MICRONS AND PROVIDING A REMAINING CENTRAL REGION OF SEMICONDUCTIVE MATERIAL AT THE POINT SUPPORTING SAID ISLAND OF ABOUT 0.5 MICRONS, REMOVING SAID RESIST ARRAY TO PROVIDE A LARGE AREA OF FIELD EMITTERS COMPRISED OF A SUBSTRATE OF SEMICONDUCTIVE MATERIAL WITH A PLURALITY OF PROJECTING ELECTRON EMITTERS EXTENDING FROM SAID SUBSTRATE IN A CRYSTALLOGRAPHICALLY CONTINUOUS MANNER IN WHICH SAID PROJECTING ELECTRON EMITTERS COMPRISE AN EMITTING POINT HAVING A DIAMETER OF ABOUT 0.5 MICRONS.
Claim 3
Dependent Claim
18 words
The method set forth in claim 1 in which said resist pattern includes a coating of silicon nitride.