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Optoelectronic 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.

Optoelectronics wafer material
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–