In this article we compare x-ray photoelectron spectroscopy (XPS) measurements on bare-and cappedzirconium nitride (ZrN) films to investigate the effect of ambient sample oxidation on the detected bound O in the form of oxide ZrO2 and/or oxynitride ZrOxNy. ZrN films in both bare-and Al2O3/AlN capped-XPS samples were grown by plasma-enhanced atomic layer deposition (PEALD) technique using tetrakis dimethylamino zirconium (TDMAZr) precursor, forming gas (5% H-2, rest N-2) inductively coupled plasma (ICP), and as received research grade process gases under identical process conditions. Capped samples were prepared by depositing 1 nm thick PEALD AlN on ZrN, followed by additional deposition of 1 nm thick ALD Al2O3, without venting of ALD reactor. On bare ZrN sample at room temperature, spectroscopic ellipsometry (SE) measurements with increasing ambient exposure times (t(exp)) showed a self-limiting surface oxidation with the oxide thickness (d(ox)) approaching 3.7 +/- 0.02 nm for t(exp) > 120 min. In XPS data measured prior to sample sputtering (t(sput) = 0), ZrO2 and ZrOxNy were detected in bare-samples, whereas only ZrN and Al2O3/AlN from capping layer were detected in capped-samples. For bare-ZrN samples, appearance of ZrO2 and ZrOxNy up to sputter depth (d(sput)) of 15 nm in depth-profile XPS data is in contradiction with measured d(ox) = 3.7 nm, but explained from sputtering induced atomic inter-diffusion within analyzed sample. Appearance of artifacts in the XPS spectra from moderately sputtered (d(sput) = 0.2 nm and 0.4 nm) capped-ZrN sample, provides an evidence to ion-bombardment induced modifications within analyzed sample. (C) 2017 Elsevier B.V. All rights reserved.