I have to do RF sputtering for MoO3 for my LED project. But I have come across many recipes for reactive RF sputtering of MoO3 ,using Mo as a target and Oxygen as the reactive gas But I want to RF sputter MoO3 directly (not via Mo target and then react it with Oxygen). Can anyone suggest me a good recipe for that?

1. You should find your recipe varying sputtering parameters (power, pressure, gas, distance, substrate temperature), looking for material properties you would like (conductivity, transparency, density, deposition rate, whatever,..).

Consider MoO3 is dielectric and there must be a power density threshold not to overcome, to avoid target cracking.

Moreover, when you sputter from a stoichiometric oxide target, you usually get a film with some oxygen deficiency (e.g. O vacancy is believe to be responsible for the n-type conductivity in sputtered ZnO). In your case, you might produce a bit of MoO2, which has different physical properties than MoO3 (e.g. band gap). If you have any hint it is happening, you must sputter in a mixture of Ar/O2 to compensate. You should plan a series to determine the best amount of O2 to get the desidered phase, maximise the deposition rate and/or prevent voids incorporations.

Some indication to start can be:

- Power: just below what is suggested by target producer;

- Pressure: around 5E-3 mbar, move from 1E-3 (with magnetron) to 1E-2 to identify the best;

- Distance: depending from your equipment, use data from previous RF-sputtered material;

- Temperature: depending if you aims to crystalline or amorphous material (consider deposition rate drops with increasing substrate T) - post-dep annealing is also a chance but higher T would be involved for cystallisation;

- Gas: start with Ar only, identify the best recipe (above parameters) and then introduce O2 if needed (usually O2 flux is some % of total flux).

2. Sputtering recipes are highly specific of the apparatus used since especially RF sputtering is highly affected by the specific chamber geometry. This may lead to variations of ideal pressures/gas fluxes/powers over several orders of magnitude.

3. You can deposit MoOx thin film with MoO3 target in Ar atmosphere (100 sccm). Vary substrate temp. from 150-200 degree C and vary RF power from150 W to 250 W to optimize the film quality. Do not forget to rotate the substrate holder @>70RPM/Min. You can anneal the deposited film at 400 degree C to obtain low resistivity

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