Quantum transport properties of industrial $^{28}$Si/$^{28}$SiO$_2$

TL;DR

This study demonstrates the fabrication and characterization of high-quality isotopically enriched $^{28}$Si/$^{28}$SiO$_2$ stacks on industrial wafers, showing promising quantum transport properties for spin qubit applications.

Contribution

First demonstration of wafer-scale $^{28}$Si/$^{28}$SiO$_2$ with detailed quantum transport characterization for industrial spin qubit platforms.

Findings

Peak mobility of 9800 cm$^2$/Vs at 1.7 K

Critical conduction density of $1.75×10^{11}$ cm$^{-2}$

Interface roughness of 0.4 nm and valley splitting up to 480 μeV

Abstract

We investigate the structural and quantum transport properties of isotopically enriched $^{28}$Si/$^{28}$SiO$_2$ stacks deposited on 300 mm Si wafers in an industrial CMOS fab. Highly uniform films are obtained with an isotopic purity greater than 99.92\%. Hall-bar transistors with an equivalent oxide thickness of 17 nm are fabricated in an academic cleanroom. A critical density for conduction of $1.75\times10^{11}$ cm$^{-2}$ and a peak mobility of 9800 cm$^2$/Vs are measured at a temperature of 1.7 K. The $^{28}$Si/$^{28}$SiO$_2$ interface is characterized by a roughness of $\Delta=0.4$ nm and a correlation length of $\Lambda=3.4$ nm. An upper bound for valley splitting energy of 480 $\mu$eV is estimated at an effective electric field of 9.5 MV/m. These results support the use of wafer-scale $^{28}$Si/$^{28}$SiO$_2$ as a promising material platform to manufacture industrial spin qubits.