Description
Silicon metal-oxide semiconductor (MOS) device structures are vital for realizing quantum computing devices based on single atoms acting as qubits in silicon. The atoms forming the qubits must be located within about 20 nm of the Si/SiO2 interface in these devices to allow control electrodes and read-out structures to work. [1] These qubits typically are based on storing quantum information in electron-nuclear spin states and are very sensitive to fluctuating electric and magnetic fields associated with charge and spin defects in the vicinity of the qubit. Probing the quality of the Si/SiO2 interface is crucial for advancing quantum applications, as quantum states are susceptible to decoherence from environmental interactions. This work focuses on the in-house fabrication of metal-oxide-semiconductor field-effect transistors (MOSFETs) and optimizing techniques for probing interface defects at temperatures down to and below 4K, where quantum devices typically operate. These defects, acting as trapping and scattering centers, influence the functionality and characteristics of the MOSFET devices and this allows these defect states to be probed and quantified. We employ charge pumping (CP) to probe these defects, utilizing substrate current measurements under periodic gate pulses to drive the device between accumulation and inversion states. [2] This method enables precise quantification of trap densities, as well as their energy and spatial distributions, with high sensitivity and simplicity. We present our findings for as-fabricated un implanted control devices and ErO implanted MOSFET devices, where erbium (Er) is selected for its potential in quantum communication applications.[3]
[1] Chatterjee et al., “Semiconductor qubits in practice,” Nat. Rev. Phys., 3, pp. 157–177 (2021).
[2] Djezzar, “Odyssey of the charge pumping technique and its applications,” J. Appl. Phys., 134, 220701 (2023).
[3] Berkman et al., “Long optical and electron spin coherence times for erbium ions in silicon,” npj Quantum Inf., 11, 66 (2025).
| I am the presenting author | Yes |
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