Silicon based quantum dot structure and quantum dot arrays incorporating blind contacts
A novel and useful mechanism of improving the controllability of the electrostatic potential profile and electric field between barrier/control gates separating quantum dots (QD) in a quantum dot array (QDA) and creating elongated double quantum dot array 2D structures each having capability for a continuous tunneling within the array structure. Plunger gates implemented as blind contacts improve electric field control between barrier gates in a quantum dot array. Blind contacts create a dedicated control potential under multiple blind contact electrodes placed on a metal layer of a standard FDSOI process. They function to control potential well depths independently for neighboring quantum dots. Two or more coupled quantum dots within one elongated active area enables interconnection of neighboring quantum dot chains using a conductive semiconductor well. The blind contacts enable the implementation of charge sensors, precise precharge transistors, and linear and 2D quantum dot array.
1 . A quantum structure, comprising:
a substrate;
a substantially undoped layer fabricated on said substrate including an active channel;
a raised source and drain fabricated on said substantially undoped layer;
one or more barrier gates fabricated on said substantially undoped layer between said raised source and drain and operative to control a potential barrier between quantum dots on either side of said one or more barrier gates; and
one or more metal blind contacts not in contact with said active channel, disposed between said one or more barrier gates and above quantum dots located between the one or more barrier gates, said one or more metal blind contacts operative to provide additional dedicated control of an electrostatic potential profile and electric field of quantum dots between said one or more barrier gates.
2 . The quantum structure according to claim 1 , wherein a dielectric below each blind contact is selected from a group consisting of silicon dioxide, silicide, aluminum oxide, hafnium oxide, tantalum oxide, low-k dielectric, and silicon nitride.
3 . The quantum structure according to claim 1 , wherein said substantially undoped layer is formed as a silicon on insulator or as a 3D structure over a bulk silicon wafer.
4 . The quantum structure according to claim 1 , further comprising an electronic spin resonance (ESR) metal strip operative to generate ac magnetic field pulses to control quantum dot spin rotation.
5 . The quantum structure according to claim 1 , further comprising a back gate biased to provide additional tuning of a shape of the quantum dots.
6 . The quantum structure according to claim 1 , wherein the fabrication of said one or more metal blind contacts allows a decreased effective gate pitch than would otherwise be possible to fabricate in a given process technology.
7 . A quantum structure, comprising:
a substrate;
a substantially undoped layer fabricated on said substrate including an active channel;
a quantum dot array (QDA) fabricated on said substantially undoped layer, said QDA comprising:
a plurality of barrier gates fabricated on said substantially undoped layer between a raised source and drain, each barrier gate operative to control a potential barrier between adjacent quantum dots;
a plurality of blind contacts not in contact with said active channel, each blind contact disposed between adjacent barrier gates and fabricated in a metal layer above a quantum dot, said blind contacts operative to provide additional control of energy of a respective quantum dot; and
a single electron transistor (SET) charge sensor fabricated in close proximity to said QDA on said undoped layer and operative to detect a presence or absence of charge in said QDA.
8 . The quantum structure according to claim 7 , wherein a dielectric below each blind contact is selected from a group consisting of silicon dioxide, silicide, aluminum oxide, hafnium oxide, tantalum oxide, low-k dielectric, and silicon nitride.
9 . The quantum structure according to claim 7 , wherein said substantially undoped layer is formed as a silicon on insulator or as a 3D structure over a bulk silicon wafer.
10 . The quantum structure according to claim 7 , further comprising a back gate common for the entire quantum structure and biased to provide additional tuning of a shape of the quantum dots.
11 . The quantum structure according to claim 7 , further comprising an electronic spin resonance (ESR) metal strip operative to generate ac magnetic field pulses to control quantum dot spin rotation.
12 . A quantum structure, comprising:
a substrate;
a substantially undoped layer fabricated on said substrate including an active channel;
a quantum dot array (QDA) fabricated on said substantially undoped layer, said QDA comprising:
a plurality of barrier gates fabricated on said substantially undoped layer between a source and drain, each barrier gate operative to control a potential barrier between adjacent quantum dots;
a plurality of blind contacts not in contact with said active channel, each blind contact disposed between adjacent barrier gates and fabricated in a metal layer above a quantum dot, said blind contacts operative to provide additional control of energy of a respective quantum dot;
a plurality of sensors/injectors fabricated on said substantially undoped layer and operative to inject and detect one or more particles in said QDA; and
wherein said QDA and sensors/injectors are arranged in an ‘H’ shape configuration rotated 45 degrees from an alignment line.
13 . The quantum structure according to claim 12 , wherein a dielectric below each blind contact is selected from a group consisting of silicon dioxide, silicide, aluminum oxide, hafnium oxide, tantalum oxide, low-k dielectric, and silicon nitride.
14 . The quantum structure according to claim 12 , wherein said undoped layer is formed as a silicon on insulator or as a 3D structure over a bulk silicon wafer.
15 . The quantum structure according to claim 12 , further comprising a back gate common for the entire quantum structure and biased to provide additional tuning of a shape of the quantum dots.
16 . The quantum structure according to claim 12 , further comprising an electronic spin resonance (ESR) metal strip operative to generate ac magnetic field pulses to control quantum dot spin rotation.