Table 2 Summary of the temperature sweep, XPS, and AFM results for each surface treatment.

From: Surface modification and coherence in lithium niobate SAW resonators

Surface treatment

\(\overline{F \delta ^0_\text {TLS}}\)

Pre-GCIB O/Nb

Pre-GCIB C/Nb

AFM surface morphology

AFM roughness \(R_q\) [pm]

CLN

\(5.8\times 10^{-6}\)

3.78

3.83

Pitted/Soft height variations

172

Annealed

\(2.48\times 10^{-5}\)

3.19

0.78

Atomically-flat islands

172

BOE

\(7.7\times 10^{-6}\)

2.91

1.38

Atomically-flat islands

175

MgO

\(1.24\times 10^{-5}\)

N/A

N/A

Pitted

560

Piranha

\(1.06\times 10^{-5}\)

2.97

0.14

Soft height variations

170

GCIB

\(7.53\times 10^{-5}\)

N/A

N/A

Pitted/Soft height variations

180

  1. Reported \(F \delta ^0_\text {TLS}\) is calculated from the average of all fitted resonances of each surface type. XPS numbers reported are the averaged oxygen and carbon atomic percentage ratios before performing the in-situ GCIB sputter. AFM results are reported as both the summary of surface morphology types and roughness. MgO and GCIB devices are not compared to other samples after XPS measurement because of other atomic species present (Mg and Al, respectively).
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