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

2. 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 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

3. 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

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

5. 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

6. 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

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

8. 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