A method of forming a p-n junction device comprises providing a base layer including a p-type diamond. A monolayer or few layer of a transition metal dichalcogenide (TMDC) is disposed on at least a portion of the base layer so as to form a heterojunction therebetween. The TMDC monolayer is an n-type layer such that the heterojunction between the intrinsic and p-type diamond base layer and the n-type TMDC monolayer is a p-n junction.

A plate varactor includes a dielectric substrate and a first electrode embedded in a surface of the substrate. A capacitor dielectric layer is disposed over the first electrode, and a layer of graphene is formed over the dielectric layer to contribute a quantum capacitance component to the dielectric layer. An upper electrode is formed on the layer of graphene. Other embodiments and methods for fabrication are also included.

A method for making a semiconductor device may include forming at least one a double-barrier resonant tunneling diode (DBRTD) by forming a first doped semiconductor layer, and a forming first barrier layer on the first doped semiconductor layer and including a superlattice. The method may further include forming a first intrinsic semiconductor layer on the first barrier layer, forming a second barrier layer on the first intrinsic semiconductor layer and also comprising the superlattice, forming a second intrinsic semiconductor layer on the second barrier layer, and forming a third barrier layer on the second intrinsic semiconductor layer and also comprising the superlattice. The method may further include forming a third intrinsic semiconductor layer on the third barrier layer, forming a fourth barrier layer on the third intrinsic semiconductor layer, and forming a second doped semiconductor layer on the fourth barrier layer.

A semiconductor device may include at least one double-barrier resonant tunneling diode (DBRTD). The at least one DBRTD may include a first doped semiconductor layer and a first barrier layer on the first doped semiconductor layer and including a superlattice. The superlattice may include stacked groups of layers, each group of layers including a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions. The at least one DBRTD may further include an intrinsic semiconductor layer on the first barrier layer, a second barrier layer on the intrinsic semiconductor layer, and a second doped semiconductor layer on the second superlattice layer.

A method for making a semiconductor device may include forming at least one double-barrier resonant tunneling diode (DBRTD) by forming a first doped semiconductor layer, and forming a first barrier layer on the first doped semiconductor layer and including a superlattice. The superlattice may include stacked groups of layers, each group of layers including stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions. The method may further include forming an intrinsic semiconductor layer on the first barrier layer, forming a second barrier layer on the intrinsic semiconductor layer, and forming a second doped semiconductor layer on the second superlattice layer.

A semiconductor device including at least one double-barrier resonant tunneling diode (DBRTD) is provided. The at least one DBRTD may include a first doped semiconductor layer, and a first barrier layer on the first doped semiconductor layer and including a superlattice. The DBRTD may further include a first intrinsic semiconductor layer on the first barrier layer, a second barrier layer on the first intrinsic semiconductor layer and also including the superlattice, a second intrinsic semiconductor layer on the second barrier layer, a third barrier layer on the second intrinsic semiconductor layer and also including the superlattice. A third intrinsic semiconductor layer may be on the third barrier layer, a fourth barrier layer may be on the third intrinsic semiconductor layer and also including the superlattice, a second doped semiconductor layer on the fourth barrier layer.