Semiconductor devices consisting of epitaxial material

Claim 2

A semiconductor device (10; 20; 30; 40) consisting of epitaxial material, characterised in that it includes at least one Dirac-delta doped monoatomic layer (13; 28, 29; 35; 45, 46) of doping atoms.

Claim 3

A semiconductor device in accordance with claim 1, characterised in that the semiconductor device is a field effect transistor (10) having source (15, 18), drain (17, 19) and gate (16) regions; and in that the or each Dirac-delta doped monoatomic layer (13) extends between said source (15, 18) and drain (17, 19) regions.

Claim 4

A semiconductor device in accordance with claim 2, characterised in that said material comprises, homogeneous semiconductor material (11).

Claim 5

A semiconductor device in accordance with claim 2, characterised in that said material has a hetero structure (Fig. ld) consisting of first and second layers of distinct semiconductor materials having different band gaps; in that said source and drain regions extend through one of said layers at least part-way into the other; and in that the or each Dirac-delta doped monoatomic layer is disposed in said material having the greater band gap.

Claim 6

A semiconductor device in accordance with claim 2, characterised in that said material has a superlattice structure (Fig. lf, lh, lg) consisting of alternating layers of first and second distinct semiconductor materials having different band gaps; in that said source and drain regions extend through several of said layers; and in that at least one Dirac-delta doped monoatomic layer is present in each of the alternating layers of the semiconducting material having the smaller band gap.

Claim 7

A semiconductor device in accordance with claim 1, characterised in that the device is an impatt diode 20 and comprises in sequence a first layer of a highly doped n-type substrate (21), a second layer of a highly doped n-type material (22), a third layer of intrinsic material (23), a fourth layer of n-type material (24) and a fifth layer of highly doped p-type material (25), with the contacts (26, 27) being connected to said fifth layer and to at least one (21) of said first and second layers (21, 22); in that a first Dirac-delta doped monoatomic layer of donors (28) is present between said second and third layers and in that a second Dirac-delta doped monoatomic layer of acceptors (29) is present between said fourth and fifth layers.

Claim 8

A semiconductor device in accordance with claim 1, characterised in that the device is a bipolar transistor (30) comprising in sequence a first layer of a highly doped n-type substrate (31), a second layer of n-type material (32), a Dirac-delta doped monoatomic layer of acceptors (35), a third layer of highly doped n-type material (33), and a fourth layer of very highly doped n-type material; and in that the collector contact (36) is formed on at least one (31) of said first and second layers (31, 32), the base contact (38) on said Dirac-delta doped monoatomic layer (35) and the emitter contact (37) on said fourth layer.

Claim 9

A semiconductor device in accordance with claim 1, characterised in that the device is an injection diode (40) comprising in sequence a first layer (41) of a highly doped n-type semiconducting substrate, a second layer of a highly doped n-type semiconducting material (42), a third layer of a distinct intrinsic semiconducting material (43) and a fourth layer (44) of a highly doped p-type version of the material of said second layer (42), with first and second electrical connections (47, 48) being provided to said fourth layer (44) and to at least one of said first and second layers (41, 42); and in that one or more pairs of Dirac-delta doped monoatomic layers (45, 46) are provided in said third intrinsic layer (43), with the first Dirac-delta doped monoatomic layer (45) of each pair comprising a monoatomic layer of donors and with the second Dirac-delta doped monoatomic layer (46) of each pair comprising a monoatomic layer of acceptors positioned parallel to and spaced apart from the associated first Dirac-delta doped layer (45) on the side thereof facing said fourth layer (44).

Claim 10

A semiconductor device in accordance with claim 8, characterised in that one side face of said device parallel to the direction of said sequence is specularly reflecting (49) and in that a second side face extending parallel to the first side face is partially reflective (50) thereby producing said laser action.

Claim 11

A semiconductor device in accordance with claim 1, characterised in that the semiconductor material is gallium arsenide.

Claim 12

A semiconductor device in accordance with claim 4, wherein one of the two distinct semiconductor materials comprises gallium arsenide GaAs and the other comprises aluminium gallium arsenide Al x Ga 1-x As.

Claim 13

A semiconductor device in accordance with claim 5, wherein one of the two distinct semiconductor materials comprises gallium arsenide GaAs and the other comprises aluminium gallium arsenide Al x Ga 1-x As.

Claim 14

A semiconductor device in accordance with claim 8, wherein one of the two distinct semiconductor materials comprises gallian alsenide GaAs and the other comprises aluminium gallium arsenide Al x Ga 1-x As.

Claim 15

A semiconductor device in accordance with claim 1 in the form of a semiconductor light wave detector, said device being characterised by a first layer (53) of a highly doped n-type semiconducting substrate, by a second layer (54) of a highly doped netype semiconducting material, by a third layer (55) of a distinct intrinsic semiconducting material and by a fourth layer (56) of a highly doped n-type semiconducting material similar to said second layer (54), with first and second electrical connections being provided to said fourth layer and to at least one of said first and second layers; the device being further characterised by a plurality of pairs of Dirac-delta doped monoatomic layers (57, 57', 58, 58') provided in said third intrinsic layer (55), with the first D irac-delta doped monoatomic layer (57; 58) of each pair (57, 57'; 58, 58') comprising a monoatomic layer of donors, and with the second Dirac-delta doped monoatomic layer (57', 58') of each pair (57, 57'; 58, 58') comprising a monoatomic layer of acceptors positioned parallel to and spaced apart from the associated first Dirac-delta doped layer (57; 58) on the side thereof facing said fourth layer (56).

Claim 16

A semiconductor device in accordance with claim 1 in the form of an optically bistable semiconductor device, characterised in that the device comprises, in sequence, a first layer (63) of an n-type semiconducting substrate, which may be doped or undoped, a series of alternatingly n-type and p-type Dirac-delta doped monoatomic layers (62, 63, 64, 65, 66, 67, 68, 69) formed on said substrate with each said Dirac-delta doped monoatomic layer (61 to 69) being separated from the next adjacent Dirac-delta doped monoatomic layer by a layer (70) of pure undoped intrinsic semiconductor material.

Claim 17

A semiconductor device in accordance with claim 1, wherein the doping concentration in the or each D irac-delta doped monoatomic layer lies in the range from 10 11 to 10 14 cm -2 .