USA As Represented by Secretary of the Navy

Steven W Kirchoefer

Douglas B Chrisey

Manfred Kahn

James S Horwitz

Jeffrey M Pond

Wontae Chang

Adriaan Carter

A semiconductor device includes a plurality of barrier layers and a plurality of quantum well layers which are alternately interleaved with each other and disposed on a substrate of semiconductor material so as to form a multiple-heterojunction varactor diode. The barrier layers and quantum well layers are doped with impurities. The varactor diode includes an ohmic contact which is electrically connected to a heavily doped embedded region and a Schottky contact which is electrically connected to a depletion region of the diode. The ohmic contact and the Schottky contact enable an external voltage source to be applied to the contacts so as to provide a bias voltage to the varactor diode. A variable capacitance is produced as a result of the depletion region varying with a variation in the bias voltage. The varactor diode also provides a constant series resistance.

Semiconductor varactor diode with doped heterojunction

A multicomponent film on a substrate can be annealed at higher temperatures in oxygen by using a specifically designed annealing vessel. The vessel is formed of a multicomponent material which has at least all of the components of the first multicomponent material of the film or, in the case where there are nonvolatile components, then the vessel is formed of a second multicomponent material which has at least the same composition of relatively volatile components as the first multicomponent film. As the multicomponent film is annealed for a sufficient time within the vessel the multicomponent film remains in contact with a vapor of the first multicomponent material and the vessel material. This process called bomb annealing prevents loss of volatile components from the film and roughening of the film surface and leads to films with lower dielectric loss. Preferred thin film materials are ferroelectric materials although any material could be used. The annealing can be done in oxygen at temperatures higher than 900&deg; C.

Bomb annealing of thin films

A quantum well electron barrier diode comprising a substrate, a first buffer layer on the substrate, a superlattice structure on the first buffer layer, a second buffer layer on the superlattice structure, a contacting layer on the second buffer layer and first and second ohmic contacts attached to the contacting layer and substrate respectively. The superlattice structure comprises a sequence of a plurality of high energy gap barrier layers interleaved with a plurality of low energy gap wells. The sequence is repeated until the desired thickness is reached. Current flows perpendicular to the layers.

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Bowie, MD, United States of America

Steven W Kirchoefer