Publications

112 Results
Skip to search filters

All-electrical universal control of a double quantum dot qubit in silicon MOS

Technical Digest - International Electron Devices Meeting, IEDM

Harvey-Collard, Patrick; Jock, Ryan M.; Jacobson, Noah T.; Baczewski, Andrew D.; Mounce, Andrew M.; Curry, Matthew J.; Ward, Daniel R.; Anderson, John M.; Manginell, Ronald P.; Wendt, J.R.; Rudolph, Martin R.; Pluym, Tammy P.; Lilly, Michael L.; Pioro-Ladrière, Michel; Carroll, Malcolm

Qubits based on transistor-like Si MOS nanodevices are promising for quantum computing. In this work, we demonstrate a double quantum dot spin qubit that is all-electrically controlled without the need for any external components, like micromagnets, that could complicate integration. Universal control of the qubit is achieved through spin-orbit-like and exchange interactions. Using single shot readout, we show both DC- and AC-control techniques. The fabrication technology used is completely compatible with CMOS.

More Details
TYPE Conference Poster YEAR 2018
ScopusOSTI

Ion implantation for deterministic single atom devices

Review of Scientific Instruments

Pacheco, Jose L.; Singh, M.; Perry, Daniel L.; Wendt, J.R.; Ten Eyck, Gregory A.; Manginell, Ronald P.; Pluym, Tammy P.; Luhman, Dwight R.; Lilly, M.P.; Carroll, Malcolm; Bielejec, E.

We demonstrate a capability of deterministic doping at the single atom level using a combination of direct write focused ion beam and solid-state ion detectors. The focused ion beam system can position a single ion to within 35 nm of a targeted location and the detection system is sensitive to single low energy heavy ions. This platform can be used to deterministically fabricate single atom devices in materials where the nanostructure and ion detectors can be integrated, including donor-based qubits in Si and color centers in diamond.

More Details
TYPE Journal Article YEAR 2017
ScopusOSTIDOI

Tunnel coupling tuning of a QD-donor S-T qubit

Jock, Ryan M.; Jock, Ryan M.; Rudolph, Martin R.; Rudolph, Martin R.; Harvey-Collard, Patrick H.; Harvey-Collard, Patrick H.; Jacobson, Noah T.; Jacobson, Noah T.; Wendt, J.R.; Wendt, J.R.; Pluym, Tammy P.; Pluym, Tammy P.; Dominguez, Jason J.; Dominguez, Jason J.; Manginell, Ronald P.; Manginell, Ronald P.; Lilly, Michael L.; Lilly, Michael L.; Carroll, Malcolm; Carroll, Malcolm

Abstract not provided.

More Details
TYPE Conference Poster YEAR 2017
OSTI

Coupling MOS quantum dot and phosphorous donor qubit systems

Technical Digest - International Electron Devices Meeting, IEDM

Rudolph, Martin R.; Harvey-Collard, P.; Jock, R.; Jacobson, Noah T.; Wendt, J.R.; Pluym, Tammy P.; Dominguez, Jason J.; Ten Eyck, Gregory A.; Manginell, Ronald P.; Lilly, M.P.; Carroll, Malcolm

Si-MOS based QD qubits are attractive due to their similarity to the current semiconductor industry. We introduce a highly tunable MOS foundry compatible qubit design that couples an electrostatic quantum dot (QD) with an implanted donor. We show for the first time coherent two-axis control of a two-electron spin logical qubit that evolves under the QD-donor exchange interaction and the hyperfine interaction with the donor nucleus. The two interactions are tuned electrically with surface gate voltages to provide control of both qubit axes. Qubit decoherence is influenced by charge noise, which is of similar strength as epitaxial systems like GaAs and Si/SiGe.

More Details
TYPE Conference Poster YEAR 2017
ScopusOSTIDOI

Coupling MOS quantum dot and phosphorous donor qubit systems

IEEE International Electron Devices Meeting

Rudolph, Martin R.; Jock, Ryan M.; Jacobson, Noah T.; Wendt, J.R.; Pluym, Tammy P.; Dominguez, Jason J.; Ten Eyck, Gregory A.; Manginell, Ronald P.; Lilly, Michael L.; Carroll, Malcolm; Harvey-Collard, Patrick H.

Si-MOS based QD qubits are attractive due to their similarity to the current semiconductor industry. We introduce a highly tunable MOS foundry compatible qubit design that couples an electrostatic quantum dot (QD) with an implanted donor. We show for the first time coherent two-axis control of a two-electron spin logical qubit that evolves under the QD-donor exchange interaction and the hyperfine interaction with the donor nucleus. The two interactions are tuned electrically with surface gate voltages to provide control of both qubit axes. Qubit decoherence is influenced by charge noise, which is of similar strength as epitaxial systems like GaAs and Si/SiGe.

More Details
TYPE Journal Article YEAR 2016
OSTIDOI

Fabrication of quantum dots in undoped Si/Si0.8Ge0.2 heterostructures using a single metal-gate layer

Applied Physics Letters

Lu, Tzu-Ming L.; Gamble, John K.; Muller, Richard P.; Nielsen, Erik N.; Bethke, D.; Ten Eyck, Gregory A.; Pluym, Tammy P.; Wendt, J.R.; Dominguez, Jason J.; Lilly, M.P.; Carroll, Malcolm; Wanke, M.C.

Enhancement-mode Si/SiGe electron quantum dots have been pursued extensively by many groups for their potential in quantum computing. Most of the reported dot designs utilize multiple metal-gate layers and use Si/SiGe heterostructures with Ge concentration close to 30%. Here, we report the fabrication and low-temperature characterization of quantum dots in the Si/Si0.8Ge0.2 heterostructures using only one metal-gate layer. We find that the threshold voltage of a channel narrower than 1 μm increases as the width decreases. The higher threshold can be attributed to the combination of quantum confinement and disorder. We also find that the lower Ge ratio used here leads to a narrower operational gate bias range. The higher threshold combined with the limited gate bias range constrains the device design of lithographic quantum dots. We incorporate such considerations in our device design and demonstrate a quantum dot that can be tuned from a single dot to a double dot. The device uses only a single metal-gate layer, greatly simplifying device design and fabrication.

More Details
TYPE Journal Article YEAR 2016
ScopusOSTIDOI

Single shot spin readout using a cryogenic high-electron-mobility transistor amplifier at sub-Kelvin temperatures

Applied Physics Letters

Tracy, Lisa A.; Luhman, Dwight R.; Carr, Stephen M.; Bishop, N.C.; Ten Eyck, Gregory A.; Pluym, Tammy P.; Wendt, J.R.; Lilly, M.P.; Carroll, Malcolm

We use a cryogenic high-electron-mobility transistor circuit to amplify the current from a single electron transistor, allowing for demonstration of single shot readout of an electron spin on a single P donor in Si with 100 kHz bandwidth and a signal to noise ratio of ∼9. In order to reduce the impact of cable capacitance, the amplifier is located adjacent to the Si sample, at the mixing chamber stage of a dilution refrigerator. For a current gain of ∼ 2.7 × 10 3, the power dissipation of the amplifier is 13 μW, the bandwidth is ∼ 1.3 MHz, and for frequencies above 300 kHz the current noise referred to input is ≤ 70 fA/ Hz. With this amplification scheme, we are able to observe coherent oscillations of a P donor electron spin in isotopically enriched 28Si with 96% visibility.

More Details
TYPE Journal Article YEAR 2016
ScopusOSTIDOI

Silicon Quantum Dots with Counted Antimony Donor Implants

Sandia journal manuscript; Not yet accepted for publication

Singh, Meenakshi S.; Pacheco, Jose L.; Perry, Daniel L.; Ten Eyck, Gregory A.; Wendt, J.R.; Pluym, Tammy P.; Dominguez, Jason J.; Manginell, Ronald P.; Luhman, Dwight R.; Bielejec, Edward S.; Lilly, Michael L.; Carroll, Malcolm

Deterministic control over the location and number of donors is crucial to donor spin quantum bits (qubits) in semiconductor based quantum computing. A focused ion beam is used to implant close to quantum dots. Ion detectors are integrated next to the quantum dots to sense the implants. The numbers of ions implanted can be counted to a precision of a single ion. Regular coulomb blockade is observed from the quantum dots. Charge offsets indicative of donor ionization, are observed in devices with counted implants.

More Details
TYPE Journal Article YEAR 2015
OSTI

Charge Sensed Pauli Blockade in a Metal–Oxide–Semiconductor Lateral Double Quantum Dot

Nano Letters

Nguyen, Khoi T.; Lu, Tzu-Ming L.; Muller, Richard P.; Carroll, Malcolm; Lilly, Michael L.; Nielsen, Erik N.; Bishop, Nathaniel B.; Young, Ralph W.; Wendt, J.R.; Dominguez, Jason J.; Pluym, Tammy P.; Stevens, Jeffrey S.

We report Pauli blockade in a multielectron silicon metal–oxide–semiconductor double quantum dot with an integrated charge sensor. The current is rectified up to a blockade energy of 0.18 ± 0.03 meV. The blockade energy is analogous to singlet–triplet splitting in a two electron double quantum dot. Built-in imbalances of tunnel rates in the MOS DQD obfuscate some edges of the bias triangles. A method to extract the bias triangles is described, and a numeric rate-equation simulation is used to understand the effect of tunneling imbalances and finite temperature on charge stability (honeycomb) diagram, in particular the identification of missing and shifting edges. A bound on relaxation time of the triplet-like state is also obtained from this measurement.

More Details
TYPE Journal Article YEAR 2013
OSTIDOI

Microfabrication of Microsystem-Enabled Photovoltaic (MEPV) cells

Proceedings of SPIE - The International Society for Optical Engineering

Nielson, Gregory N.; Okandan, Murat O.; Cruz-Campa, Jose L.; Resnick, Paul J.; Wanlass, Mark W.; Clews, Peggy J.; Pluym, Tammy P.; Sanchez, Carlos A.; Gupta, Vipin P.

Microsystem-Enabled Photovoltaic (MEPV) cells allow solar PV systems to take advantage of scaling benefits that occur as solar cells are reduced in size. We have developed MEPV cells that are 5 to 20 microns thick and down to 250 microns across. We have developed and demonstrated crystalline silicon (c-Si) cells with solar conversion efficiencies of 14.9%, and gallium arsenide (GaAs) cells with a conversion efficiency of 11.36%. In pursuing this work, we have identified over twenty scaling benefits that reduce PV system cost, improve performance, or allow new functionality. To create these cells, we have combined microfabrication techniques from various microsystem technologies. We have focused our development efforts on creating a process flow that uses standard equipment and standard wafer thicknesses, allows all high-temperature processing to be performed prior to release, and allows the remaining post-release wafer to be reprocessed and reused. The c-Si cell junctions are created using a backside point-contact PV cell process. The GaAs cells have an epitaxially grown junction. Despite the horizontal junction, these cells also are backside contacted. We provide recent developments and details for all steps of the process including junction creation, surface passivation, metallization, and release.

More Details
TYPE Conference YEAR 2011
ScopusOSTI

Thin and small form factor cells : simulated behavior

Cruz-Campa, Jose L.; Okandan, Murat O.; Resnick, Paul J.; Grubbs, Robert K.; Clews, Peggy J.; Pluym, Tammy P.; Young, Ralph W.; Gupta, Vipin P.; Nielson, Gregory N.

Thin and small form factor cells have been researched lately by several research groups around the world due to possible lower assembly costs and reduced material consumption with higher efficiencies. Given the popularity of these devices, it is important to have detailed information about the behavior of these devices. Simulation of fabrication processes and device performance reveals some of the advantages and behavior of solar cells that are thin and small. Three main effects were studied: the effect of surface recombination on the optimum thickness, efficiency, and current density, the effect of contact distance on the efficiency for thin cells, and lastly the effect of surface recombination on the grams per Watt-peak. Results show that high efficiency can be obtained in thin devices if they are well-passivated and the distance between contacts is short. Furthermore, the ratio of grams per Watt-peak is greatly reduced as the device is thinned.

More Details
TYPE Conference YEAR 2010
OSTI

Back-contacted and small form factor GaAs solar cell

Cruz-Campa, Jose L.; Nielson, Gregory N.; Okandan, Murat O.; Sanchez, Carlos A.; Resnick, Paul J.; Clews, Peggy J.; Pluym, Tammy P.; Gupta, Vipin P.

We present a newly developed microsystem enabled, back-contacted, shade-free GaAs solar cell. Using microsystem tools, we created sturdy 3 {micro}m thick devices with lateral dimensions of 250 {micro}m, 500 {micro}m, 1 mm, and 2 mm. The fabrication procedure and the results of characterization tests are discussed. The highest efficiency cell had a lateral size of 500 {micro}m and a conversion efficiency of 10%, open circuit voltage of 0.9 V and a current density of 14.9 mA/cm{sup 2} under one-sun illumination.

More Details
TYPE Conference YEAR 2010
OSTI

Back contacted and small form factor GAAS solar cell

Cruz-Campa, Jose L.; Nielson, Gregory N.; Okandan, Murat O.; Sanchez, Carlos A.; Resnick, Paul J.; Clews, Peggy J.; Pluym, Tammy P.; Gupta, Vipin P.

We present a newly developed microsystem enabled, back-contacted, shade-free GaAs solar cell. Using microsystem tools, we created sturdy 3 {micro}m thick devices with lateral dimensions of 250 {micro}m, 500 {micro}m, 1 mm, and 2 mm. The fabrication procedure and the results of characterization tests are discussed. The highest efficiency cell had a lateral size of 500 {micro}m and a conversion efficiency of 10%, open circuit voltage of 0.9 V and a current density of 14.9 mA/cm{sup 2} under one-sun illumination.

More Details
TYPE Conference YEAR 2010
OSTI
112 Results
112 Results