We report CMOS-compatible quantized current sources (electron pumps) fabricated with nanowires (NWs) on 300mm SOI wafers. Unlike other Al, GaAs or Si based metallic or semiconductor pumps, the fabrication does not rely on electron-beam lithography. The structure consists of two gates in series on the nanowire and the only difference with the SOI nanowire process lies in long (40nm) nitride spacers. As a result a single, silicide island gets isolated between the gates and transport is dominated by Coulomb blockade at cryogenic temperatures thanks to the small size and therefore capacitance of this island. Operation and performances comparable to devices fabricated using e-beam lithography is demonstrated in the non-adiabatic pumping regime, with a pumping frequency up to 300MHz. We also identify and model signatures of charge traps affecting charge pumping in the adiabatic regime. The availability of quantized current references in a process close to the 28FDSOI technology could trigger new applications for these pumps and allow to cointegrate them with cryogenic CMOS circuits, for instance in the emerging field of interfaces with quantum bits.

Recent breakthroughs in silicon spin quantum bits motivate the effort to develop a whole set of conventional CMOS circuits to provide a low-noise, dedicated interface with the qubits, operating at low temperature. In this spirit we have developed a ring-oscillator based circuit designed to generate RF signals on chip, as well as new electron pumps fabricated using only optical lithography, thus making them compatible with massively parallel fabrication with high yield. Design, cryogenic operation and performances are discussed.

The definition of the ampere will change in the next few years. This electrical base unit of the S.I. will be redefined by fixing the value of the charge quantum, i.e., the electron charge e. As a result electron pumps will become the natural device for the mise en pratique of this new ampere. In the last years semiconductor electron pumps have emerged as the most advanced systems, both in terms of speed and precision. Another figure of merit for a metrological device would be its ability to be predictible and shared. For that reason a mature fabrication process would certainly be an advantage. In this article we present electron pumps made within a CMOS (Complementary Metal Oxide Semiconductor) research facility on 300mm silicon-on-insulator wafers, using advanced microelectronics tools and processes. We give an overview of the whole integration scheme and emphasize the fabrication steps which differ from the normal CMOS route.

Silicon-On-Insulator nanowire transistors of very small dimensions exhibit quantum effects like Coulomb blockade or single-dopant transport at low temperature. The same process also yields excellent field-effect transistors (FETs) for larger dimensions, allowing to design integrated circuits. Using the same process, we have co-integrated a FET-based ring oscillator circuit operating at cryogenic temperature which generates a radio-frequency (RF) signal on the gate of a nanoscale device showing Coulomb oscillations. We observe rectification of the RF signal, in good agreement with modeling.

We present the co-integration of a ring-oscillator based CMOS circuit purposely designed to drive RF signals onto the gates of a single-electron device. It is fabricated on 300 mm wafers with the nanowire silicon-on-insulator technology and operated at cryogenic temperatures. Using the same technology for both the classical circuit and the quantum device is a unique opportunity which is implemented by simply changing the width of the field-effect transistors. While 25 nm widths yield devices behaving as quantum devices, 1μm relaxed widths guarantee a safe operation of the CMOS circuit since its components behave as regular Field-Effect transistors. We demonstrate the operation of the circuit at low temperature and observed the generation of DC currents in the absence of any applied DC bias. The generated DC current can be well explained in the framework of a rectification model [8]. The successful operation of such a co-integrated circuit can be very promising for future integration of quantum nanoelectronic devices.

We present a model for the operation of a single-island adiabatic electron pump with field-effect transistors acting as tunable barriers. We account for the electrostatics by modeling the capacitive network and fit the parameters of the gate-dependent barrier conductances which include exponential dependence in the subthreshold regime. This procedure results in the knowledge of the parametric dependence of the tunneling rates in the master equation for sequential tunneling. We compute the pumping current by numerically integrating the time-dependent master equation along a closed contour traversed in the gate voltage plane by the two out-of-phase harmonic signals that drive the pump. Basic features expected for a quantized adiabatic pump are reproduced by the calculation which will be extended to explore and differentiate the error mechanisms of the pump.

Electron pumps capable of delivering a current higher than 100 pA with sufficient accuracy are likely to become the direct mise en pratique of the possible new quantum definition of the am-pere. Furthermore, they are essential for closing the quantum metrological triangle experiment which tests for possible corrections to the quantum relations linking e and h, the electron charge and the Planck constant, to voltage, resistance and current. We present here single-island hybrid metal/semiconductor transistor pumps which combine the simplicity and efficiency of Coulomb blockade in metals with the unsurpassed performances of silicon switches. Robust and simple pumping at 650 MHz and 0.5 K is demonstrated. The pumped current obtained over a voltage bias range of 1.4 mV corresponds to a relative deviation of 5×10 −4 from the calculated value, well within the 1.5×10 −3 uncertainty of the measurement setup. Multi-charge pumping can be performed. The simple design fully integrated in an industrial CMOS process makes it an ideal candidate for national measurement institutes to realize and share a future quantum ampere.