we consider the annealing study performed on the samples which were grown simultaneously (samples A–F). Each sample was initialized into the UV state and measured by IR and EPR to quantify the defects present — see Table \[tab:quantification\_methods\] for details on quantification method for each defect.

[Sample A]{}is dominated by nitrogen-related complexes, with the most abundant identified defects being [$\mathrm{N_{s}^{0}}$]{}$^{/+}$ and [${\ensuremath{\mathrm{NVH}}\xspace}^{0}$]{}$^{/-}$ \[Fig. \[fig:annealing\]\]. The only identified silicon-related centres are [$\mathrm{SiV}^{0}$]{}$^{/-}$ which are present at approximately combined. Any concentrations of [$\mathrm{SiVH}^0$]{} [@Edmonds2008a] and [$\mathrm{SiV_2H}^0$]{} [@DHaenens-Johansson2010] are below EPR detection limits ($\SI{\approx1}{\ppb}$). [Sample A]{}is visually brown but heavily photo/thermochromic, varying from deep brown to brown-pink in the UV and heated states, respectively.

![Point defect concentrations measured by EPR and IR in samples grown simultaneously and subsequently annealed for at high temperature under stabilizing pressure (see Table \[tab:sample\_summary\]). All measurements taken with the sample in the UV-treated charge state (see text for details). Dashed lines are guides to the eye.[]{data-label="fig:annealing"}](graphs_combined_concentrations_uv_from_epr){width="\columnwidth"}

[lp[0.3cm]{}lp[0.3cm]{}Sc]{} Defect && Technique && &\
[$\mathrm{N_{s}^{0}}$]{} && IR && & [@Woods1990]\
[$\mathrm{N_{s}^{+}}$]{} && IR && & [@Lawson1998]\
[${\ensuremath{\mathrm{NVH}}\xspace}^{0}$]{} && IR && & [@Liggins2010b]\
[${\ensuremath{\mathrm{NVH}}\xspace}^{-}$]{} && EPR && & [@Glover2003a]\
[${\ensuremath{\mathrm{N_2VH}}\xspace}^{0}$]{} && EPR && & [@Hartland2014]\
[${\ensuremath{\mathrm{N_3VH}}\xspace}^{0}$]{}&& IR && & [@Hartland2014]\
[$\mathrm{SiV}^{0}$]{} 