Few-electron edge-state quantum dots in a silicon nanowire field-effect transistor.

We investigate the gate-induced onset of few-electron regime through the undoped channel of a silicon nanowire field-effect transistor. By combining low-temperature transport measurements and self-consistent calculations, we reveal the formation of one-dimensional conduction modes localized at the two upper edges of the channel. Charge traps in the gate dielectric cause electron localization along these edge modes, creating elongated quantum dots with characteristic lengths of ∼10 nm. We observe single-electron tunneling across two such dots in parallel, specifically one in each channel edge. We identify the filling of these quantum dots with the first few electrons, measuring addition energies of a few tens of millielectron volts and level spacings of the order of 1 meV, which we ascribe to the valley orbit splitting. The total removal of valley degeneracy leaves only a 2-fold spin degeneracy, making edge quantum dots potentially promising candidates for silicon spin qubits.

[1]  R. S. Ross,et al.  Pauli spin blockade in undoped Si/SiGe two-electron double quantum dots , 2011, 1106.6285.

[2]  Charles M Lieber,et al.  Coherent single charge transport in molecular-scale silicon nanowires. , 2005, Nano letters.

[3]  Isabelle Ferain,et al.  Multigate transistors as the future of classical metal–oxide–semiconductor field-effect transistors , 2011, Nature.

[4]  S. Sarma,et al.  Intervalley coupling for interface-bound electrons in silicon: An effective mass study , 2010, 1006.3338.

[5]  Michelle Y. Simmons,et al.  Silicon quantum electronics , 2012, 1206.5202.

[6]  B. Previtali,et al.  A tunable, dual mode field-effect or single electron transistor , 2012, 1201.3760.

[7]  M. Vinet,et al.  Background charges and quantum effects in quantum dots transport spectroscopy , 2008, 0810.0672.

[8]  Charles M Lieber,et al.  Spin states of the first four holes in a silicon nanowire quantum dot. , 2008, Nano letters.

[9]  Hongwen Jiang,et al.  Parallel spin filling and energy spectroscopy in few-electron Si metal-on-semiconductor-based quantum dots , 2010 .

[10]  X Jehl,et al.  Detection of a large valley-orbit splitting in silicon with two-donor spectroscopy. , 2012, Physical review letters.

[11]  M. Lagally,et al.  Single-electron quantum dot in Si∕SiGe with integrated charge sensing , 2007, 0710.3725.

[12]  V. Trivedi,et al.  Suppression of corner effects in triple-gate MOSFETs , 2003, IEEE Electron Device Letters.

[13]  Gerhard Klimeck,et al.  Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting , 2013, Nature Communications.

[14]  H. Huebl,et al.  Observation of the single-electron regime in a highly tunable silicon quantum dot , 2009, 0910.0576.

[15]  C. Yang,et al.  Spin filling of valley–orbit states in a silicon quantum dot , 2011, Nanotechnology.

[16]  M. Mouis,et al.  Carrier transport in HfO/sub 2//metal gate MOSFETs: physical insight into critical parameters , 2006, IEEE Transactions on Electron Devices.

[17]  Ferry,et al.  Surface roughness at the Si(100)-SiO2 interface. , 1985, Physical review. B, Condensed matter.

[18]  Insoo Woo,et al.  Gate-induced quantum-confinement transition of a single dopant atom in a silicon FinFET , 2008 .

[19]  Romain Wacquez,et al.  Few electron limit of n-type metal oxide semiconductor single electron transistors , 2012, Nanotechnology.

[20]  F. Stern,et al.  Electronic properties of two-dimensional systems , 1982 .

[21]  L. Dreeskornfeld,et al.  A comprehensive study of corner effects in tri-gate transistors , 2004, Proceedings of the 30th European Solid-State Circuits Conference (IEEE Cat. No.04EX850).

[22]  D. Rideau,et al.  Quantum calculations of the carrier mobility: Methodology, Matthiessen's rule, and comparison with semi-classical approaches , 2013, 1310.1704.

[23]  X Jehl,et al.  Single-donor ionization energies in a nanoscale CMOS channel. , 2010, Nature nanotechnology.

[24]  C. Tavernier,et al.  Onsite matrix elements of the tight-binding Hamiltonian of a strained crystal: Application to silicon, germanium, and their alloys , 2009, 0902.0491.

[25]  Toshiro Hiramoto,et al.  Quantum mechanical effects in the silicon quantum dot in a single-electron transistor , 1997 .

[26]  Y. Taur.  An analytical solution to a double-gate MOSFET with undoped body , 2000 .