Boron 1s binding energies collated from [1].
The boron 1s peak has a low photoelectron cross-section and detection limits are generally 1 at. % or more. Significant peak overlaps are known for P 2s and plasmon loss structure from the Si 2s peak.

[1] C.D. Wagner, A.V. Naumkin, A. Kraut-Vass, J.W. Allison, C.J. Powell, J.R.Jr. Rumble, NIST Standard Reference Database 20, Version 3.4 (web version) (http:/ 2003.