- Nb-SrTiO₃ (Niobium Doped Strontium Titanate) Single Crystal Substrate
- Custom doping concentration between 0.05-1 wt%
- Commonly used as substrate for: Perovskites e.g. LaAlO₃, YBCO, BiFeO₃, BaxSr1-xTiO₃, SrRuO₃, and many complex oxide perovskites including titanates, aluminates, ferrites, zirconates and stannates.
- <0.2 nm rms roughness (measured 5x5 µm AFM scan)
Nb-doped STO is used to grow films (often perovskites) where a electrical connection is required for the device being created or the testing of the film. We stock Nb-Concentration 0.7 wt% which gives good conductivity without shifting the lattice parameter too much therefore similar films can be grown as with SrTiO₃. We can also provide this in 0.05%, 0.1% or 0.5% and 1% if required.
Cost Considerations Nb-STO (Nb-SrTiO₃)
Due to the processing of Nb-STO it is more expensive than STO, so typically people get their growth conditions right on STO before transitioning over to Nb-STO. Or at least the films which do not require electrical connection are grown on STO.
In Nb Doped STO - Nb5+ substitutes Ti4+ in the lattice, bringing more oxide ions or more electrons into the system. In the range of 0.05-1 wt% this dramatically increases the electrical conductivity, the resistivity continues to drop with Nb content from around 0.07 ohm.cm at 0.05 wt% Nb doping to 0.004 ohm.cm at 0.7% Nb. For a full write up on SrTiO₃, please refer to the SrTiO₃ product page here.
Alternatives to Nb-SrTiO₃ (Nb-STO) Crystal Substrates
An alternative to using Nb-SrTiO₃ is depositing a thin layer of highly conducting (metal like) SrRuO₃ - this is a lattice matched material with metal like conductivity and even a 20 nm layer can be used as a good electrical connection. It has high conductivity but can lead to difficulties in making the connection to the film if subsequent layers are very thick. SrRuO₃ are readily grown by PLD at around 600C -700 C and 150 mTorr. Ruthenium makes the targets expensive to make and it is difficult to make them very dense so they last for a few years at a time. You can buy targets from www.target-materials.com
If you have any questions please contact us here.
Dr Joseph Franklin
| LINEAR FORMULA: | Nb 0.7% SrTiO3 |
| PURITY: | >99.99% |
| CRYSTAL ORIENTATION: | (100), (110) & (111) |
| GROWTH METHOD: | Vernuil |
| CRYSTAL STRUCTURE: | Cubic |
| LATTICE CONSTANT: | a=3.905 A |
| MELTING POINT (°C): | 2080 |
| THERMAL EXPANSION COEFFICIENT (/K): | 10.4 |
| HARDNESS: | 6 |
| MOLAR MASS (G/MOL): | 183.80 |
| DENSITY (G/CM3): | 5.175 |
| REFRACTIVE INDEX: | 2.3 to 2.5 in the visible spectrum. |
| DIELECTRIC CONSTANTS: | 300 at room temperature |
| CHEMICAL STABILITY: | Insoluble in water |
| SIZES: | 5x5mm & 10x10 mm |
| TYPICAL THICKNESS: | 0.5mm |
| SIZE TOLERANCES: | +/- 0.1mm |
| THICKNESS TOLERANCES: | +/- 0.015mm |
| ORIENTATION PRECISION: | +/-0.5 degree |
| POLISHING OPTIONS: | SINGLE SIDED (1SP) OR BOTH SIDES POLISHED (2SP) |
| ROUGHNESS RA: | <0.5nm |
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How long does it take for you to ship out after purchase? In-Stock Substrates are held in our US warehouse and we aim to have substrates shipped out within 24-48 hours.
Pre-Order Substrates are manufactured and delivered in 3-4 weeks.
How much is shipping? All substrates are shipped free of charge within the USA. This shipping takes approx 4-5 days to arrive once shipped.
Expedited delivery? Faster delivery options are available. Below are some indicative prices. To get the cost for your package and location, just add your address at check out and select the shipping option you want to check.
- USA FedEx 2 day delivery: typically $25 USD
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