Semiconductor device having a selectively doped heterostructure

Claim 2

A semiconductor device having a selectively doped heterostructure, comprising: a semiconductor substrate having a top surface; a channel layer of an undoped semiconductor material having a top surface, being provided on the top surface of the semiconductor substrate; a carrier supplying layer of a doped semiconductor material having a top surface, being provided on the top surface of the channel layer for supplying carriers, said channel layer and said carrier supplying layer forming a heterojunction interface at a boundary between the channel layer and the carrier supplying layer with a two-dimensional electron gas formed in the channel layer along the heterojunction interface; said doped semiconductor material forming the carrier supplying layer and said undoped semiconductor material forming the channel layer having respective compositions determined such that the Γ valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the Γ valley of the conduction band of the channel layer at the heterojunction interface, the L valley of the conduction band of the carrier supplying layer has an energy level higher than corresponding energy level of the L valley of the conduction band of the channel layer at the heterojunction interface, the X valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the X valley of the conduction band at the heterojunction interface, the energy level of the Γ valley of the conduction band of the carrier supplying layer is equal to or higher than the energy level of the L valley of the conduction band of the channel layer at the heterojunction interface, and the energy level of the L valley of the conduction band of the carrier supplying is equal to of higher than the energy level of the X valley of the conduction band of the channel layer at the heterojunction interface; a first electrode provided on the top surface of the carrier supplying layer for injecting carriers into the two-dimensional electron gas through the carrier supplying layer; a second electrode provided on the top surface of the carrier supplying layer with a separation from the first electrode, for collecting the carriers injected through the first electrode which flow through the two-dimensional electron gas to the second electrode; and control electrode means provided on the top surface of the carrier supplying layer between the first electrode and the second electrode, for controlling a flow of the carriers injected through the first electrode means which flow through the two-dimensional electron gas, said doped semiconductor material forming the carrier supplying layer comprising gallium indium phosphide having a composition represented as In 0 .44 Ga 0 .56 P and the channel layer comprising gallium arsenide.

Claim 3

A semiconductor device having a selectively doped heterostructure, comprising: a semiconductor substrate having a top surface; a channel layer of an undoped semiconductor material having a top surface, being provided on the top surface of the semiconductor substrate; a carrier supplying layer of a doped semiconductor material having a top surface, being provided on the top surface of the channel layer for supplying carriers, said channel layer and said carrier supplying layer forming a heterojunction interface at a boundary between the channel layer and the carrier supplying layer with a two-dimensional electron gas formed in the channel layer along the heterojunction interface; said doped semiconductor material forming the carrier supplying layer and said undoped semiconductor material forming the channel layer having respective compositions determined such that the Γ valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the Γ valley of the conduction band of the channel layer at the heterojunction interface, the L valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the L valley of the conduction band of the channel layer at the heterojunction interface, the X valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the X valley of the conduction band at the heterojunction interface, the energy level of the Γ valley of the conduction band of the carrier supplying layer is equal to or higher than the energy level of the L valley of the conduction band of the channel layer at the heterojunction interface, and the energy level of the L valley of the conduction band of the carrier supplying layer is equal to or higher than the energy level of the X valley of the conduction band of the channel layer at the heterojunction interface; a first electrode provided on the top surface of the carrier supplying layer for injecting carriers into the two-dimensional electron gas through the carrier supplying layer; a second electrode provided on the top surface of the carrier supplying layer with a separation from the first electrode for collecting the carriers injected through the first electrode which flow through the two-dimensional electron gas to the second electrode; and control electrode means provided on the top surface of the carrier supplying layer between the first electrode and the second electrode for controlling a flow of the carriers injected through the first electrode means which flow through the two-dimensional electron gas. said carrier supplying layer comprising a first layer of said doped semiconductor material and a second layer grown on said first layer, said second layer having a composition so determined as to establish a matching of a crystal lattice of the carrier supplying layer and a crystal lattice of the channel layer.

Claim 4

A semiconductor device having a selectively doped heterostructure, comprising: a semiconductor substrate having a top surface; a channel layer of an undoped semiconductor material having a top surface, being provided on the top surface of the semiconductor substrate; a carrier supplying layer of a doped semiconductor material having a top surface, being provided on the top surface of the channel layer for supplying carriers, said channel layer and said carrier supplying layer forming a heterojunction interface at a boundary between the channel layer and the carrier supplying layer with a two-dimensional electron gas formed in the channel layer along the heterojunction interface; said doped semiconductor material forming the carrier supplying layer and said undoped semiconductor material forming the channel layer having respective compositions determined such that the Γ valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the Γ valley of the conduction band of the channel layer at the heterojunction interface, the L valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the L valley of the conduction band of the channel layer at the heterojunction interface, the X valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the X valley of the conduction band at the heterojunction interface, the energy level of the Γ valley of the conduction band of the carrier supplying layer is equal to or higher than the energy level of the L valley of the conduction band of the channel layer at the heterojunction interface, and the energy level of the L valley of the conduction band of the carrier supplying layer is equal to or higher than the energy level of the X valley of the conduction band of the channel layer at the heterojunction interface; a first electrode provided on the top surface of the carrier supplying layer for injecting carriers into the two-dimensional electron gas through the carrier supplying layer; a second electrode provided on the top surface of the carrier supplying layer with a separation from the first electrode for collecting the carriers injected through the first electrode which flow through the two-dimensional electron gas to the second electrode; and control electrode means provided on the top surface of the carrier supplying layer between the first electrode and the second electrode for controlling a flow of the carriers injected through the first electrode means which flow through the two-dimensional electron gas. said carrier supplying layer comprising a first layer of said doped semiconductor material and a second layer grown on said first layer, said second layer having a composition so determined as to establish a matching of a crystal lattice of the carrier supplying layer and a crystal lattice of the channel layer.

Claim 5

A semiconductor device as claimed in claim 2, wherein said second layer has a composition of In 0 .484 Ga 0 .516 P.

Claim 6

A semiconductor device having a selectively doped heterostructure, comprising: a semiconductor substrate having a top surface; a channel layer of an undoped semiconductor material having a top surface, being provided on the top surface of the semiconductor substrate; a carrier supplying layer of a doped semiconductor material having a top surface, being provided on the top surface of the channel layer for supplying carriers, said channel layer and said carrier supplying layer forming a heterojunction interface at a boundary between the channel layer and the carrier supplying layer with a two-dimensional electron gas formed in the channel layer along the heterojunction interface; said doped semiconductor material forming the carrier supplying layer and said undoped semiconductor material forming the channel layer having respective compositions determined such that the Γ valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the Γ valley of the conduction band of the channel layer at the heterojunction interface, the L valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the L valley of the conduction band of the channel layer at the heterojunction interface, the X valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the X valley of the conduction band at the heterojunction interface, the energy level of the Γ valley of the conduction band of the carrier supplying layer is equal to or higher than the energy level of the L valley of the conduction band of the channel layer at the heterojunction interface, and the energy level of the L valley of the conduction band of the carrier supplying layer is equal to or higher than the energy level of the X valley of the conduction band of the channel layer at the heterojunction interface; a first electrode provided on the top surface of the carrier supplying layer for injecting carriers into the two-dimensional electron gas through the carrier supplying layer; a second electrode provided on the top surface of the carrier supplying layer with a separation from the first electrode, for collecting the carriers injected through the first electrode which flow through the two-dimensional electron gas to the second electrode; and control electrode means provided on the top surface of the carrier supplying layer between the first electrode and the second electrode, for controlling a flow of the carriers injected through the first electrode means which flow through the two-dimensional electron gas. said doped semiconductor material forming the carrier supplying layer comprises aluminum gallium arsenide antimonide having a composition of Al x Ga 1-x As 0 .48 Sb 0 .52 with a compositional parameter X chosen to be equal to or larger than 0.35 and the channel layer comprising Ga 0 .53 In 0 .47 As which is lattice-matched to indium phosphide.

Claim 7

A semiconductor device having a selectively doped heterostructure, comprising: a semiconductor substrate having a top surface; a channel layer of an undoped semiconductor material having a top surface, being provided on the top surface of the semiconductor substrate; a carrier supplying layer of a doped semiconductor material having a top surface, being provided on the top surface of the channel layer for supplying carriers, said channel layer and said carrier supplying layer forming a heterojunction interface at a boundary between the channel layer and the carrier supplying layer with a two-dimensional electron gas formed in the channel layer along the heterojunction interface; said doped semiconductor material forming the carrier supplying layer and said undoped semiconductor material forming the channel layer having respective compositions determined such that the Γ valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the Γ valley of the conduction band of the channel layer at the heterojunction interface, the L valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the L valley of the conduction band of the channel layer at the heterojunction interface, the X valley of the conduction band of the carrier supplying layer has an energy level higher than a corresponding energy level of the X valley of the conduction band at the heterojunction interface, the energy level of the Γ valley of the conduction band of the carrier supplying layer is equal to or higher than the energy level of the L valley of the conduction band of the channel layer at the heterojunction interface, and the energy level of the L valley of the conduction band of the carrier supplying layer is equal to or higher than the energy level of the X valley of the conduction band of the channel layer at the heterojunction interface; a first electrode provided on the top surface of the carrier supplying layer for injecting carriers into the two-dimensional electron gas through the carrier supplying layer; a second electrode provided on the top surface of the carrier supplying layer with a separation from the first electrode, for collecting the carriers injected through the first electrode which flow through the two-dimensional electron gas to the second electrode; and control electrode means provided on the top surface of the carrier supplying layer between the first electrode and the second electrode, for controlling a flow of the carriers injected through the first electrode means which flow through the two-dimensional electron gas. said doped semiconductor material forming the carrier supplying layer comprises aluminum gallium arsenide antimonide having a composition of Al x Ga 1-x As 0 .48 Sb 0 .52 with a compositional parameter X chosen to be equal to or larger than 0.35 and the channel layer comprising Ga 0 .53 In 0 .47 As which is lattice-matched to indium phosphide.