Semiconductor Device Group

We have developed an 8 nm diameter silicon nanowire process which has been used to produce sensors, transistors and quantum dots which form the basis of current standards and qubits.

Current standards: We are developing single quantum dot nanowire devices using two wrap around gates which will be a turnstyle to single electrons. By running one of the gates at a frequency f, the current, I through the device is the electron charge, q times the frequency which produces a current standard with I = qf. We are working with NPL and NIST to develop a lot temperature current standard without the need for any magnetic field. By scaling the device down so the quantum dot is of order of 10 nm or less, we are aiming to produce a current standard that could work at room temperature. The vision is to produce single chip current standards that could be integrated into current meters and other scientific or consumer products to allow them to be self-calibrated to the integrated standard.

Qubits: We are working with groups at Oxford, Cambridge and UCL to produce multiple quantum dots with a range of control gates and readout devices to form charge and spin qubits.

• M.M. Mirza, F.J. Schupp, J.A. Mol, D.A. MacLaren, G.A.D. Briggs and D.J. Paul, "One dimensional transport in silicon nanowire junction-less field effect transistors" Scientific Reports 7(1), 3004 (2017) - DOI: 10.1038/s41598-017-03138-5
• C. Busche, L. Vila-Nadal, J. Yan, H.N. Miras, De-L. Long, V.P. Georgiev, A. Asenov, R.H. Pedersen, N. Gadegaard, M.M. Mirza, D.J. Paul, J.M. Poblet and L. Cronin, "Design and fabrication of memory devices based on nanoscale polyoxometalate clusters" Nature 515, Issue 7528, pp. 545 - 549 (2014) - DOI: 10.1038/nature13951
• M.M. Mirza, D.A. MacLaren, A. Samarelli, B.M. Holmes, H. Zhou, S. Thoms, D. MacIntyre and D.J. Paul, "Determining the electronic performance limitations in top-down fabricated Si nanowires with mean widths down to 4 nm" Nano Letters 14(11), pp. 6056 - 6060 (2014) - DOI: 10.1021/nl5015298
• D.J. Paul, J.R.A. Cleaver, H. Ahmed and T.E. Whall “Coulomb blockade in silicon based structures at temperatures up to 50K” Applied Physics Letters 63(5), pp631-632 (1993) - doi:10.1063/1.109972