Sn/Zr multilayers project Andriy Zakutayev Fall 2009 1/15/2019 Andriy Zakutayev

Experimental details Deposition Neocera chamber (10-5 base pressure) Sn- and Zr-metal targets, pre-polished, pre-ablated Si and SiO2 substrates, cleaned 2 J/cm2, 10Hz, RT 200 periods of Sn/Zr Sn/Zr pulse count varied Total of 20000 pulses Pressure drops after the deposition starts – Zr getters O2 in the chamber Zr particulates start coming out at ~5000 pulse count in the target (see them as sparks). No effect for Sn because of a low melting point Sn/Zr and Zr/Sn deprates are not the same as Sn/Sn and Zr/Zr - had to do deposition calibration Also tried in Ar/H2 95/5 mixture at 100 mTorr – more oxygen Anneal Gilbert 011 H2S flow furnace 2h pre-purge with Ar 50 units of flowrate 10C/min ramp times 2-o-ring seal Anneal temperature and time varried Also tried varying number of o-rings, Gilbert 15 furnace, Zr getter, 200/500C temperarutre protocol – not less oxygen 1/15/2019 Andriy Zakutayev

Broad study - EPMA As deposited Contain the same amount of oxygen Sn/Zr=1 at ~0.28 pulse ratio Annealed Sn/Zr=1 at ~0.45 pulse ratio – some Sn is lost S/Sn=1 and O/Zr=2 1/15/2019 Andriy Zakutayev

Broad study – XRD Annealed: SnS+ZrO2; (as-deposited – Sn + maybe amorphous Zr-O) 1/15/2019 Andriy Zakutayev

Anneal temperature Sn/Zr Decreases with T due to SnS loss O/Zr S/Sn Fluctuates around O/Zr=2 at all temperatures S/Sn Stays at 1 until 600C phase transition 1/15/2019 Andriy Zakutayev

Anneal time Sn/Zr Decreases with T due to SnS loss O/Zr S/Sn Fluctuates around O/Zr=2 at all temperatures S/Sn Stays at 1 until 600C phase transition 1/15/2019 Andriy Zakutayev

Spatial variation in as-deposited film ~5 at. % variation. 1 a.u. = 2mm 1/15/2019 Andriy Zakutayev

Discussion The main problem is Zr reactivity with oxygen (in the chamber and in the furnace) Possible solutions: try Thermionics for lower base pressure (but no automation); preablate for longer – getter maximal oxygen (longer ablation – Zr particles); Even if oxygen problem is solved: Sn/Zr varies with anneal T; H2S Furnace oxidizes even SnZrCh3-x films, so will oxidize Sn/Zr for sure Other thoughts: Elevated T for better mixing, but not higher than Sn melting point (230C), Will require Sn/Zr pulse ratio re-callibration. Main conclusion: Sn/Zr multilayers+H2S anneals are not an easy route to SnZrS3 thin films because of easy oxidation or Zr 1/15/2019 Andriy Zakutayev