SrTiO3 (STO) Single Crystal Substrate — (100) (110) (111)
High-purity SrTiO3 (STO) single crystal substrates feature a cubic perovskite structure (a = 3.905) engineered for advanced oxide thin-film epitaxy. Widely recognized as the industry-standard lattice-matched substrate, STO is essential for growing high-temperature superconductors (YBCO), ferroelectric films, magnetoresistive materials, and complex oxide heterostructures. Its outstanding thermal stability, dielectric properties, and crystalline perfection ensure optimal film growth with minimal interfacial strain.
We supply high-grade STO substrates in standard (100), (110), and (111) orientations with atomic-level surface polishing (Ra < 0.2 nm) on single or double sides. Available in both high-resistivity undoped and electrically Nb-doped (0.5–1.0 wt%) conductive configurations, these substrates cater directly to functional electronic, optoelectronic, and transport measurement applications. Standard sizes include 10 x 10 mm and 5 x 5 mm with 0.5 mm thickness, alongside custom geometry capabilities.
Technical Specifications
| Parameter | Value |
|---|---|
| Product | SrTiO3 (STO) — Strontium Titanate, Cubic Perovskite, Pm3m, the Most Widely Used Perovskite Substrate |
| Lattice Constant | a = 3.905 Å — the universal perovskite substrate; matches YBCO (~0.4%), LSMO, BTO, BFO, PZT |
| Density / Melting Pt | 5.12 g/cm³ | 2,080°C |
| Dielectric ε / Hardness | ε~300 at RT (1MHz) | Mohs 6-6.5 |
| Phase Transition | Cubic→Tetragonal at ~110K (antiferrodistortive — not ferroelectric) |
| Nb-Doped Resistivity | ~10⁻²-10⁻³ Ω·cm (0.05-0.5 wt% Nb) — conductive substrates for electrodes |
| R.I. / Growth Method | 2.394-2.407 @589nm | Verneuil (flame fusion) |
| Primary Applications | YBCO HTS epitaxy, STO/LAO 2DEG interfaces, ferroelectric thin-film substrates, conductive AFM/STM, oxide electronics |
Product Overview
SrTiO3 (STO) is the most widely used perovskite single crystal substrate in the world — the universal starting point for complex oxide epitaxy. With a=3.905Å, ε~300, and availability in both undoped (>10⁷ Ω·cm, insulating) and Nb-doped (10⁻²-10⁻³ Ω·cm, conductive) grades, STO is the substrate for: YBCO HTS epitaxy, the STO/LAO 2DEG (the most studied oxide interface), ferroelectric/multiferroic films, and conductive AFM/STM substrates. Princeton Powder supplies (100)(110)(111) orientations, 5×5mm to Ø2″, CMP epi-ready (Ra<0.5nm), with TiO2-terminated surface available on request.
Technical Specifications
| Parameter | Undoped STO | Nb:STO (Conductive) |
|---|---|---|
| Structure | Cubic Pm3m; a=3.905Å | |
| Resistivity | >10⁷ Ω·cm | ~10⁻²-10⁻³ Ω·cm (0.05-0.5 wt% Nb) |
| Dielectric ε | ~300 (RT, 1MHz) | |
| Density | 5.12 g/cm³ | |
| Melting Point | 2,080°C | |
| Phase Transition | Cubic→Tetragonal at ~110K (NOT ferroelectric) | |
| R.I. @589nm | 2.394-2.407 | |
| Orientations | (100)(110)(111) ±0.5° | |
| Sizes / Thickness | 5×5-20×20mm²; Ø1-2″; 0.5mm, 1.0mm ±0.05mm | |
| Polish | SSP/DSP; CMP epi-ready Ra<0.5nm (AFM); TiO2-terminated on request | |
Why Choose Princeton Powder STO
- The Universal Perovskite Substrate: Matches more perovskite oxides (YBCO, LSMO, BTO, BFO, PZT, LAO) than any other commercial substrate — the standard starting point for oxide epitaxy worldwide.
- Undoped & Nb-Doped from One Source: Insulating for epitaxy; Nb-doped conductive for bottom-electrode devices and STM/AFM substrates. Same quality, same supplier.
- TiO2-Terminated Available: Chemical etching produces atomically flat B-site termination — the preferred surface for perovskite epitaxy.
Applications
YBCO HTS Epitaxy
STO's ~0.4% lattice match to YBCO is the best of any commercial substrate — enabling Jc>10⁶ A/cm² HTS thin films for SQUIDs, microwave filters, and superconducting electronics.
STO/LAO 2D Electron Gas
The defining oxide interface — where two insulators meet to form a high-mobility 2DEG with emergent superconductivity and magnetism. Princeton Powder's TiO2-terminated STO provides the ideal starting surface.
Ferroelectric Thin Films — BTO, PZT, BFO
STO is the preferred substrate for ferroelectric memory and multiferroic epitaxy. Nb-doped STO serves as the conductive bottom electrode in capacitor device structures.
FAQ
STO vs KTaO3 vs BaTiO3?
STO: universal, cheapest, Nb-doped, widely available. KTaO3: better YBCO match, 5× Rashba SOC, quantum paraelectric. BTO: ferroelectric, giant EO. Princeton Powder supplies all three.
TiO2-terminated vs as-polished?
As-polished = mixed SrO/TiO2 termination. TiO2-terminated = chemically etched to remove SrO, leaving atomically flat TiO2 surface — the preferred surface for perovskite epitaxy.
Nb-doped vs undoped?
Undoped (>10⁷ Ω·cm): insulating — for epitaxy, dielectrics, microwave devices. Nb-doped (~10⁻² Ω·cm): conductive — for bottom-electrode capacitors, STM/AFM substrates, oxide FET contacts.