Low resistance tunnel junctions in wide band gap materials and method of making same
First Claim
1. A low resistance tunnel junction structure, comprising:
- first and second semiconductor layers, said first layer being degenerately doped n-type such that its Fermi level is located in or near its conduction band, and said second layer being degenerately doped p-type such that its Fermi level is located in or near its valence band;
a metal contact forming a junction with one of said first layer or second layer, and a substrate forming a junction with the other one of said first layer or second layer;
a third semiconductor layer having a dissimilar composition from said first and second layers sandwiched between, in contact with and forming first and second heterojunction contacts with said first and second layers respectively; and
said first, second and third layers establishing a tunnel junction and having an associated natural polarization dipole that aligns said first layer'"'"'s conduction band to said second layer'"'"'s valence band so that the tunnel junction width is smaller than it would be in the absence of said third layer.
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Abstract
A low resistance tunnel junction that uses a natural polarization dipole associated with dissimilar materials to align a conduction band to a valence band is disclosed. Aligning the conduction band to the valence band of the junction encourages tunneling across the junction. The tunneling is encouraged, because the dipole space charge bends the energy bands, and shortens a tunnel junction width charge carriers must traverse to tunnel across the junction. Placing impurities within or near the tunnel junction that may form deep states in the junction may also encourage tunneling in a tunnel junction. These states shorten the distance charge carriers must traverse across the tunnel junction.
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Citations
21 Claims
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1. A low resistance tunnel junction structure, comprising:
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first and second semiconductor layers, said first layer being degenerately doped n-type such that its Fermi level is located in or near its conduction band, and said second layer being degenerately doped p-type such that its Fermi level is located in or near its valence band; a metal contact forming a junction with one of said first layer or second layer, and a substrate forming a junction with the other one of said first layer or second layer; a third semiconductor layer having a dissimilar composition from said first and second layers sandwiched between, in contact with and forming first and second heterojunction contacts with said first and second layers respectively; and said first, second and third layers establishing a tunnel junction and having an associated natural polarization dipole that aligns said first layer'"'"'s conduction band to said second layer'"'"'s valence band so that the tunnel junction width is smaller than it would be in the absence of said third layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A low resistance tunnel junction structure comprising:
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a first layer of a first material having a first type of doping such that its Fermi level is in or near a first energy band, wherein said first layer is degenerately doped with said first type of doping, a second layer of a second material in semiconductor junction contact with said first layer, a third layer of said first material having a second type of doping such that its Fermi level is in or near a second energy band in semiconductor junction contact with said second layer, wherein said third layer is degenerately doped with said second type of doping, said first, second and third layers establish a tunnel junction and having an associated polarization dipole generated by the presence of said second layer that aligns said first layers said first band to said third layers said second band and forms a tunnel junction width that is smaller than it would be in the absence of said second layer; and a metal contact forming a junction with one of said first layer or second layer, and a substrate forming a junction with the other one of said first layer or second layer. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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Specification