Semiconductor varactor diode with doped heterojunction

A varactor diode comprising:

• a substrate of semiconducting material;
• a plurality of barrier layers and a plurality of quantum-well layers alternately interleaved with each other and disposed on said substrate so as to form a multiple quantum-well heterostructure, wherein the barrier layers and quantum-well layers together have an average doping density of a value resulting in a charge screening length which is larger by a factor of at least two than the sum of a single barrier layer thickness and a single quantum-well layer thickness;
• a depletion region formed in said multiple quantum-well heterostructure;
• an embedded region formed in said multiple quantum-well heterostructure so as to be electrically connected to each of said barrier layers and each of said quantum-well layers;
• and
• a substrate contact electrically connected to said embedded region and a region contact electrically connected to said depletion region for enabling an external voltage to be applied between said substrate contact and said region contact so as to cause a variation in said depletion region as a result of a variation in the external voltage.

A varactor diode comprising:

• a substrate of semiconducting material;
• a plurality of barrier layers and a plurality of undepleted quantum-well layers providing a primary conductive path, said barrier layers and said undepleted quantum-well layers being alternately interleaved with each other and being formed on said substrate;
• a depletion region including a depletion front disposed adjacent to, and extending parallel to, said primary conductive path, wherein said depletion region comprises a predetermined number of said plurality of barrier layers and a predetermined number of said plurality of quantum-well layers, wherein each of said predetermined number of barrier layers is doped with an n-type impurity concentration of 1×1016 cm−3, and wherein each of said predetermined number of quantum-well layers is doped with an n-type impurity concentration of at least 1×1018 cm−3;
• a doped region operatively connected to each of said barrier layers and to each of said undepleted quantum-well layers;
• and
• a substrate contact electrically connected to said doped region and a region contact electrically connected to said depletion region for enabling an external bias to be applied so as to cause a variation in said depletion front thereby providing a constant series resistance in said primary conductive path.

A variable capacitance diode comprising:

• a substrate of semiconducting material;
• a plurality of barrier layers and a plurality of undepleted quantum-well layers alternately interleaved with each other and formed on said substrate, wherein each of said barrier layers is doped with an n-type impurity concentration of 1×1016 cm−3, and wherein each of said predetermined number of quantum-well layers is doped with an n-type impurity concentration of at least 1×1018 cm−3;
• a depletion region including a depletion front, a predetermined number of said plurality of barrier layers and a plurality of depleted quantum-well layers;
• a primary conductive path formed of said undepleted quantum-well layers, said primary conductive path disposed adjacent to and extending parallel to said depletion front;
• a heavily-doped region formed within said substrate so as to be electrically connected to each of said barrier layers and to each of said undepleted quantum-well layers;
• and
• a substrate contact electrically connected to said heavily-doped region and a region contact electrically connected to said depletion region for enabling an external voltage to be applied so as to cause a variation in said depletion front thereby providing a constant series resistance in said primary conductive path.

A varactor diode comprising:

• a substrate of semiconducting material;
• a plurality of barrier layers and a plurality of quantum-well layers alternately interleaved with each other and disposed on said substrate so as to form a multiple quantum-well heterostructure, wherein said plurality of barrier layers include an alloy of a first composition and wherein said plurality of quantum well layers include an alloy of a second composition;
• a depletion region formed in said multiple quantum-well heterostructure, wherein said depletion region comprises a predetermined number of said plurality of barrier layers and a predetermined number of said plurality of quantum-well layers, wherein each of said predetermined number of barrier layers is doped with an n-type impurity concentration of 1×1016 cm−3, and wherein each of said predetermined number of quantum-well layers is doped with an n-type impurity concentration of at least 1×1018 cm−3;
• an embedded region formed in said multiple quantum-well heterostructure so as to be electrically connected to each of said barrier layers and each of said quantum-well layers;
• and
• a substrate contact electrically connected to said embedded region and a region contact electrically connected to said depletion region for enabling an external voltage to be applied between said substrate contact and said region contact so as to cause a variation in said depletion region as a result of a variation in the external voltage.

A varactor diode comprising:

• a substrate of semiconducting material, wherein said substrate is heavily doped with an n-type impurity;
• a plurality of barrier layers and a plurality of quantum-well layers alternately interleaved with each other and disposed on said substrate so as to form a multiple quantum-well heterostructure;
• a depletion region formed in said multiple quantum-well heterostructure, wherein said depletion region comprises a predetermined number of said plurality of barrier layers and a predetermined number of said plurality of quantum-well layers, wherein each of said predetermined number of barrier layers is doped with an n-type impurity concentration of 1×1016 cm−3, and wherein each of said predetermined number of quantum-well layers is doped with an n-type impurity concentration of at least 1×1018 cm−3, wherein said depletion region further comprises a depletion edge extending parallel to said substrate and disposed adjacent to one of said plurality of quantum-well layers, said depletion edge moving parallel to said substrate and adjacent to a different one of said plurality of quantum-well layers as a result of a variation in said external voltage;
• an embedded region formed in said multiple quantum-well heterostructure so as to be electrically connected to each of said barrier layers and each of said quantum-well layers;
• and
• a substrate contact electrically connected to said embedded region and a region contact electrically connected to said depletion region for enabling an external voltage to be applied between said substrate contact and said region contact so as to cause a variation in said depletion region as a result of a variation in the external voltage, wherein said substrate contact comprises an annular germanium-nickel-gold ring.