Silicon substrate was cleaned prior to deposition to remove native oxide. Off-axis (90 degree) PLD was performed at around 50 m.Torr oxygen partial pressure, 1 J/S.cm fluences and 500 C temperature which resulted in amorphous SrTiO3. Where similar conditions resulted in epitaxial SrTiO3 on SrTiO3 substrate.
How do you typically characterize the Nano structure of your samples? What size are they?
Films were ~100 nm. When looking through SEM, the surfece looks grainy, clusters of ~10 nm. HRXRD/XRD also tried on those samples to get structural information which resulted no peaks.
I have deposited epitaxial Ni ferrite and Lithium ferrite (Both these are metallic oxides) using PLD long time ago. You can find these papers published in Ame..J. Appl. Phys. and CJP in 1995-2003. I used epitaxial substrates of Al2O3 with C- plane A-plane and R-plane orientations. You can buy these substrates. I could get the epitaxial films at very high temperature around 900 C. First I tried to deposit epitaxial films of these metallic oxides on polycrystalline Al2O3 substrates about three years by wasting a lot of time, and it never worked. Then finally I switched to epitaxial substrates of Al2O3, and it worked. So you have to try epitaxial (single crystal) substates and high deposition temperatures. Subsequent annealing at high temperatures also never worked.
The key problem might be the oxidation of the silicon surface at a high oxygen partial perssure and the low growth temperature. As others mentioned, a single-crystal substrate with smooth and clean surface is a prerequisite for epitaxial growth. The surface of the silicon substrates you used might react with oxygen gas in the vacuum chamber. The growth temperature might be too low for oxide epitaxial growth on silicon by PLD.
You may use up to 5 topics "up top". to get better circulation. Changing topics midstream could also create additional participation. What XRD equipment do you use for HRXRD/XRD observations? Post photos if possible.
"HRXRD/XRD also tried on those samples to get structural information which resulted no peaks" - How do you optimize your reflections for rocking curve analyses? Post your rocking curve profiles (RCP) when convenient. Do you observe the substrate RCP? What is the penetration depth estimate for your sample at the XRD conditions chosen?
When it comes to epitaxial growth, as others have pointed out, it is the parent/child paradigm generally. Epitaxial film would tend to duplicate the substrate. So, I'd pay close attention to the substrate and its surface and subsurface Nano structure. For instance, if you do use the HRXRD/XRD techniques then you must record the information prior to depositing the epitaxial film as well. It would be best to map it at several subsequently identifiable locations on the sample surface at the least.
I do have to presume that you are using the conventional 0D point counter in your "high tech" HRXRD/XRD apparatus at IISc Bengaluru. Correct? What's your effective sampling size?
Ok to call you "KV" or would you prefer a different 1st name?
I don't think that it is possible to grow STO directly on Si at that background pressure. Si is easily oxidized and forms an amorphous SiOx layer preventing epitaxy.
Usually YSZ or CeO2/YSZ is used as buffer layer for epitaxial SrTiO3 growth on Si.
MBE allows to grow SrTiO3 on Si, but ultra high vacuum, low temperature deposition and recrystallization steps are needed (see for example Li et al. J. Appl. Phys. 93, 4521 (2003))
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