Resource · Reference
Material Property Guide
Comprehensive reference for semiconductor substrate materials — silicon, GaAs, SiC, GaN, InP, sapphire, glass, and quartz with electrical, thermal, mechanical, and optical property tables.
Substrate Thin Film Materials
Material Guide Intro
Silicon (Si)
Substrate Bandgap: 1.12 eVThermal conductivity: 150 W/m·KMobility (e): 1400 cm²/V·sDensity: 2.33 g/cm³Young's modulus: 130–188 GPaThermal expansion: 2.6 ppm/KRefractive index: 3.42 (@ 1.5μm)Melting point: 1414°C
Thermal SiO₂
Dielectric Bandgap: ~9 eVBreakdown field: > 10 MV/cm (dry)Dielectric constant: 3.9Density: 2.20 g/cm³Refractive index: 1.46 (@633nm)Thermal conductivity: 1.4 W/m·KCTE: 0.5 ppm/KEtch: BOE or HF based
Si₃N₄ (Stoichiometric)
Dielectric Bandgap: ~5 eVResistivity: 10¹⁶ Ω·cmDielectric constant: 7.5Stress: 0.8–1.2 GPa (tensile)Refractive index: 2.0 (@633nm)Density: 3.17 g/cm³Young's modulus: 250 GPaEtch: hot H₃PO₄ at 160°C
Al₂O₃ (Sapphire/ALD)
Dielectric Bandgap: 6.5–7.0 eVDielectric constant: 8.0–9.5Breakdown field: 15–20 MV/cmDensity: 3.97 g/cm³Thermal conductivity: 25–40 W/m·KRefractive index: 1.76 (@633nm)CTE: 5.3 ppm/K (sapphire)Etch: BCl₃/Cl₂ RIE
Gallium Arsenide (GaAs)
Substrate Bandgap: 1.42 eV (direct)Mobility (e): 8500 cm²/V·sDensity: 5.32 g/cm³Thermal conductivity: 55 W/m·KCTE: 5.73 ppm/KBreakdown field: 0.4 MV/cmRefractive index: 3.4 (@ 1.5μm)Melting point: 1238°C
Indium Phosphide (InP)
Substrate Bandgap: 1.34 eV (direct)Mobility (e): 5400 cm²/V·sDensity: 4.81 g/cm³Thermal conductivity: 68 W/m·KCTE: 4.75 ppm/KBreakdown field: 0.5 MV/cmRefractive index: 3.2 (@ 1.5μm)Melting point: 1062°C
4H-SiC
Substrate Bandgap: 3.26 eVMobility (e): 1000 cm²/V·sBreakdown field: 2.5–3.0 MV/cmThermal conductivity: 370–490 W/m·KCTE: 3.2 ppm/K (a-axis)Density: 3.21 g/cm³Refractive index: 2.6 (@633nm)Sublimation: ~2700°C
GaN (on SiC/Si)
Substrate Bandgap: 3.4 eV (WZ)Mobility 2DEG: 1500–2200 cm²/V·sBreakdown field: 3.3 MV/cmThermal conductivity: 130–200 W/m·KCTE: 3.17 ppm/K (a-axis, bulk)Density: 6.15 g/cm³Saturation velocity: 2.5×10⁷ cm/sMelting point: > 2500°C
Borosilicate Glass (Pyrex®)
Substrate CTE: 3.25 ppm/K (matched to Si)Anodic bonding: 300–500°CDensity: 2.23 g/cm³Young's modulus: 63 GPaTg (softening): 821°CDielectric constant: 4.6 (@1MHz)Refractive index: 1.47 (@633nm)Na content: ~4% (enables anodic bonding)
Fused Silica / Quartz
Substrate CTE: 0.55 ppm/KDensity: 2.20 g/cm³Young's modulus: 73 GPaRefractive index: 1.46 (@633nm)Transmission: > 85% (UV–NIR)Tg: ~1200°CDielectric constant: 3.8 (@1MHz)Excellent UV transparency
Aluminum (Al, metallization)
Metal Resistivity: 2.65 μΩ·cmMelting point: 660°CCTE: 23.1 ppm/KDensity: 2.70 g/cm³Adhesion: Ti or Cr interlayerEtch: Cl₂/BCl₃ RIEDeposition: PVD sputteringTypical thickness: 0.5–3μm
Gold (Au, electrode/bond pad)
Metal Resistivity: 2.44 μΩ·cmMelting point: 1064°CCTE: 14.2 ppm/KDensity: 19.3 g/cm³Adhesion: Cr or Ti interlayerEtch: Ar ion milling or KI/I₂Deposition: e-beam or sputterWire bond: Au or Al wire
How To Use Guide
Material selection is a multi-parameter optimization problem. The key property decisions depend on your application: for power devices — prioritize bandgap, breakdown field, thermal conductivity; for RF/mmWave — electron mobility, saturation velocity, substrate resistivity; for MEMS — Young's modulus, residual stress, CTE match to device layers; for photonics — refractive index, optical transparency window, electro-optic coefficient; for packaging — CTE match to die, thermal conductivity, dielectric constant.