Ultra-high-speed photoconductive devices using semi-insulating layers
AssigneeMassachusetts Institute of Technology
InventorsFrank W. Smith, Mark A. Hollis, Arthur R. Calawa, Vicky Diadiuk, Han Q. Le
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Abstract
An ultra-high-speed photoconductive device is described which comprises a homoepitaxial semi-insulating III-V layer, or body, upon which ohmic/conductive contacts, or strips, separated by a small gap, are formed. The semi-insulating body, or layer, is produced by low temperature growth of III-V compounds by MBE. In a GaAs embodiment, the layer is grown under arsenic stable growth conditions, at a substrate temperature preferably in the range of 150.degree. to about 300.degree. C.
Claims13
A semiconductor photoconductive device comprising:
- a) a substrate formed of III-V species semi-insulating material;
- b) a crystalline layer on said substrate of homoepitaxial III-V species material having an excess of the more volatile of the species, said layer having a resistivity greater than or equal to 10.sup.7 ohm-cm;
- c) a conductive strip, separated by a gap on said layer and wherein, upon application of light to said gap, the layer becomes conductive and a signal applied to one side of the gap may be switched to the other side in less than 10 pico seconds.
A photoconductive device comprising:
- a) a homoepitaxial body of crystalline III-V molecular species material formed from Group III and Group IV molecular species, one of the species being more volatile than the other species;
- b) the body incorporating an excess of the more volatile of the species and having a resistivity in excess of 10.sup.7 ohm-cm;
- and
- c) a first electrical conductor on said body comprising an ohmic contact on the body with a gap separating one portion of the conductor from another portion of the conductor, and wherein upon application of light to said gap, a portion of the body underlying the gap becomes conductive such that a signal applied to one side of the gap is switched to the other side in less than 10 pico seconds.
A III-V photoconductive device comprising:
- a) a homoepitaxial crystalline layer of a compound of III material and V material formed on a substrate, one of the materials being more volatile than the other material;
- b) the homoepitaxial layer incorporating an excess of the more volatile of the materials in the homoepitaxial layer having a resistivity equal to or greater than 10.sup.7 ohm-cm;
- c) a stabilizing layer of III-V material formed over the homoepitaxial layer to minimize out diffusion of the more volatile of the materials;
- and
- d) ohmic contacts on the stabilizing layer, the contacts separated by a gap.
A high-speed photoconductive detector having a response time of less than 10 picoseconds comprising:
- a) a crystalline homoepitaxial layer of III-V material formed on a substrate, one of the III-V materials being more volatile than the other;
- b) the layer having an excess of the more volatile of the materials and a resistivity in excess of about 10.sup.7 ohm-cm;
- and
- c) an electrical conductor on the layer having a gap separating one portion of the conductor from another portion of the conductor on said layer and wherein upon application of light to said gap, the layer becomes conductive and a signal applied to one side of the gap is switched to the other side in less than 10 pico seconds.
Dependencies are inferred from the claim text.