Optoelectronics Materials

Optoelectronic Materials are Semiconductor Materials that have the ability to emit light. Silicon and Germanium are categorised as Indirect Bandgap Semiconductors and are inefficient light emitters / absorbers.

Direct Bandgap Semiconductors that possess strong absorption / emission characteristics are best suited for Optoelectronic applications such as:

  • LEDs
  • Laser Diodes
  • Photo Diodes
  • Solar Cells

Most widely used semiconductors for Optoelectronic device applications are compounds formed between elements of group III and group V of the periodic table also known as III-V Semiconductors.

Types of III-V Semiconductors include:

  • Aluminium Nitride (AlN)
  • Gallium Arsenide (GaAs)
  • Gallium Nitride (GaN)

Indirect Bandgap Semiconductors such as Silicon Carbide (SiC) can also emit light with impurities added into the material. This process is known as doping.

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Typical Specifications and Properties for Optoelectronic Materials

Aluminium Nitride (AlN) Substrates

AlN Material Properties
Typical Data
Unit of Measurement
ColourGrey – Beige
Density3.25 – 3.30g/cm3
Surface Roughness0.3 – 0.6µm
Bending Strength200 – 450MPa
Modulus of Elasticity320GPa
Vickers Hardness11GPa
Fracture Toughness3MPa.m½
Coefficient of Thermal Expansion4.4 – 5.210-6 / K
Thermal Conductivity120 – 230W/(m.K)
Specific Heat720J/(kg.K)
Dielectric Constant8.7 – 9.0
Dielectric Loss Factor0.210-3
Dielectric Strength> 15kV /mm
Volume Resistivity≥ 1014Ω.cm

Silicon Carbide (SiC) Substrates

SiC Material Properties
Typical Data
Unit of Measurement
Diameter50.8, 76.2, 100, 150mm
Thickness330 – 350µm
On-Axis Wafer Surface Orientation(0001) ± 0.5°Degrees
Off-Axis Wafer Surface Orientation4Degrees
Primary Flat Position± 5Degrees
Primary Flat Length15.9 – 47.5mm
Edge Exclusion1 – 3mm
Bow≤ 25 – 40µm
Warp≤ 25 – 60µm
TTV≤ 15µm
Resistivity0.015 – 0.028Ω.cm
Total Useable Area≤ 90%
ContaminationNone
Scratches3 – 8Wafer Size
CracksNone
ChipsNone
PinholesNone
Pits≤ 20

Gallium Arsenide (GaAs) Semi-Conducting Substrates

GaAs Semi-Conducting Material Properties
Typical Data
Unit of Measurement
Conductivity TypeP-Type / N-Type
DopantSi – Zn / Si
Diameter2”, 3”, 4” & 6”Inches
Thickness225 – 650µm
Wafer Orientation<1-0-0> ± 0.5Degrees
Carrier Concentration(0.2 – 3.5) x 1018
(0.5 – 4) x 1019
cm-3
Resistivity(1.2 – 9.9) x 10-3Ω.cm
Etch Pit Density< 500 – 3000cm-2
TTV (P/P)≤ 5µm
DTTV (P/E)≤ 10µm
Warp≤ 10µm
Surface FinishSSP / DSP
Epitaxial ReadinessYes

Gallium Arsenide (GaAs) Semi-Insulating Substrates

GaAs Semi-Insulating Material Properties
Typical Data
Unit of Measurement
Conductivity TypeInsulating
DopantUndoped
Diameter2”, 3”, 4” & 6”Inches
Thickness350 – 675µm
Wafer Orientation<1-0-0> ± 0.5Degrees
Resistivity106Ω.cm
Etch Pit Density< 5000cm-2
TTV (P/P)≤ 5µm
DTTV (P/E)≤ 10µm
Warp≤ 10µm
Surface FinishFS SSP – BS
FINE GRIND / DSP
Epitaxial ReadinessYes

Gallium Nitride (GaN) on Sapphire Substrates

GaN on Sapphire Material Properties
Typical Data
Unit of Measurement
Conductivity TypeP-Type / N-Type
DopantUndoped – Si – Mg
Diameter2”, 4”Inches
Thickness4 – 20µm
Wafer OrientationC / 0001 ± 0.5Degrees
Carrier Concentration< 5 x 1017
> 1 x 1018
> 6 x 1016
cm-3
Resistivity< 0.5
< 0.05
– 10
Ω.cm
Dislocation Density< 5 x 1018cm-2
Substrate StructureGaN on Sapphire
Surface FinishFS SSP – BS
FINE GRIND / DSP
Useable Surface Area> 90%

Gallium Nitride (GaN) Free Standing Substrates

GaN Free Standing Material Properties
Typical Data
Unit of Measurement
Conductivity TypeN-Type / Semi-Insulating
DopantUndoped – Ge – Fe
Diameter2”Inches
Thickness350µm
Wafer OrientationC / 0001 ± 0.5 OFFDegrees
TTV≤ 15 μmµm
BOW≤ 20 μmµm
Resistivity< 0.5
< 0.05
– 106
Ω.cm
Dislocation Density105 – 3 x 106cm-2
Surface FinishFS RA < 0.2nm /
BS Fine Ground
Useable Surface Area> 90%

Sapphire High Purity Single Crystal Substrates

Sapphire Material Properties
Typical Data
Unit of Measurement
Diameter2”, 4” & 6”Inches
Thickness430 – 1300µm
Wafer OrientationC-Plane to M-Plane / A-Plane
Orientation Flat Length16 – 49mm
Flat OrientationA-Plane
TTV≤ 5 – ≤ 15µm
BOW≤ 5 – ≤ 30µm
Warp≤ 10 – ≤ 40µm
Surface FinishFS RA < 3 A /
BS Fine Ground
Epitaxial ReadinessYes