Include Product Page LSAT_Material Information

• Name: LSAT, Lanthanum Strontium Aluminium Tantalate crystal substrate
• (LaAlO3)0.3(Sr2TaAlO6)0.7 or its less common alternative: (La0.18Sr0.82)(Al0.59Ta0.41)O3
• Lattice parameter: a=7.736 Å (so ½ a = 3.868 Å)
• Crystal Structure: Perovskite, Cubic
• Commonly used as substrate for: many perovskite crystals, high-T semiconductors awith relatively low strain as wells as GaN
• <0.2 nm rms roughness (measured 5x5 µm AFM scan)
• 5x5 mm to 2 inch diameter and customized
• Single or double side polished
• Optically transparent, chemically and thermally stable even in reducing atmospheres keeping low electrical conductivity across a range of deposition conditions
• Next day delivery
• Melting point 1,840 °C means that high quality crystals can be grown using the Czochralski process which keeps the cost lower than other growth methods and can be grown in larger diameter crystals than e.g. STO.

LSAT substrates are popular for epitaxial oxides and their heterostructures, often in the study of electron correlation phenomena. LSAT, along with the other perovskite substrates we stock is great for growing perovskites e,g, strontium titanate (SrTiO3), cuprate superconductors (such as YBCO), iron-based superconductors (iron-pnictides), rare-earth manganites, rare-earth nickelates and others. Semiconductors such as gallium nitride can also be grown on LSAT.

The lattice constant of LSAT is a=7.736 Å (so ½ a = 3.868 Å) so most perovskite films match with the half lattice constant of LSAT making good films with low strain. LSAT crystal has larger size and higher crystallinity than SrTiO, and it does not contain twins in the structure as does LaAlO3  which occur due to the phase transition on cooling of LAO. 

One of the differentiators of LSAT as a substrate for the growth films stems is its high chemical and thermal stability, and very low electrical conductivity across a range of temperatures. The growth conditions for some epitaxial layers can cause some substrates to form high densities of defects that can alter their properties. One example is the tendency of strontium titanate to form oxygen vacancy defects under high temperatures in high vacuum. These defects result in considerable variations of its properties, including the increase of electrical conductivity and optical opacity. LSAT on the other hand, is stable in both oxidizing and fairly reducing environments in high temperatures, thus enabling a larger window for the processing and growth conditions.

So if you’re growing perovskites or other materials at reducing conditions or at very high T then consider using LSAT.