Figure 1.

Schematic of ALD doping sequence used in CaS:Eu and CaS:EuO samples. (0) Top layers of CaS matrix. Red track represents the doping sequence in CaS:Eu sample including: (A1) Eu(thd)₃ pulsing on CaS layer, (A2) H₂S pulsing after nitrogen purge, (A3) second Eu(thd)₃ pulsing after purge, (A4) H₂S pulsing after nitrogen purge and (A5) CaS monolayer after the doping sequence. Blue track represents the doping sequence in CaS:EuO sample including: (B1) O₃ pulse on CaS layer, (B2) Eu(thd)₃ pulsing after purge, (B3) second O₃ pulsing after nitrogen purge, (B4) second Eu(thd)₃ pulsing after purge, (B5) third O₃ pulsing after nitrogen purge and (B6) CaS monolayer after the doping sequence. Atomic elements are represented with the following colors: (Ca) green, (S) yellow, (H) gray, (Eu) lavender, (O) red and (C) black.