Results and model for single-gate ratchet charge pumping

Area of Science:

• Quantum computing
• Semiconductor device physics
• Electron pumping

Background:

• Single-gate and two-gate pumping are crucial for charge transport in quantum devices.
• Silicon (Si) and Gallium Arsenide (GaAs) devices exhibit different characteristics in electron pumping.
• Understanding limitations in Si-based pumping is vital for advancing quantum technologies.

Purpose of the Study:

• To experimentally investigate the differences in single-gate and multi-gate pumping modes between Si and GaAs devices.
• To identify the underlying physical mechanisms responsible for the lack of single-gate pumping plateaus in Si devices.
• To propose strategies for improving the performance and yield of single-gate ratchet pumps in Si.

Main Methods:

• Experimental demonstration of multiple two-gate pumping modes in Si devices.
• Comparative analysis of pumping behavior in Si and GaAs devices.
• Theoretical analysis of four proposed mechanisms limiting single-gate pumping in Si.

Main Results:

• Si devices successfully demonstrated multiple two-gate pumping modes but failed in single-gate mode.
• GaAs devices exhibited high-yield single-gate pumping.
• Four mechanisms (electron number, energy ratio, nonlinear barriers, heating) were identified as potential causes for the lack of Si single-gate plateaus.

Conclusions:

• The identified mechanisms hinder single-gate ratchet pumping in Si but not two-gate pumping.
• GaAs devices are less susceptible to these failure mechanisms due to architectural differences.
• Reducing cross-capacitances and other errors can enhance Si single-gate pump robustness and yield.