Boron Phosphide (BP) Semiconductors

Topics Covered

Chemical Properties
Electrical Properties
Thermal, Mechanical and Optical Properties
Safety Information


Boron phosphide is a chemical compound of boron and phosphorus. It is a semiconductor material and is not attacked by acids or boiling aqueous alkali water solutions. Pure boron phosphide is almost transparent, though n-type crystals are orange-red in colour and p-type crystals are dark red.


Boron phosphide finds applications in the following areas:

  • Laser diodes
  • Light-emitting devices
  • Dopants
  • Protective coatings for soft infra-red transmitting substrates.

Chemical Properties

The chemical properties of boron phosphide are provided in the table below:

Chemical Properties
Chemical Formula BP
Molecular Weight 41.785
CAS No. 20205-91-8
Group Boron – 13
Phosphorus – 15
Crystal Structure Zinc blende
Lattice Constant 4.538 Å

Electrical Properties

The electrical properties of boron phosphide are provided in the table below:

Electrical Properties
Band Gap 2.1 eV
Electron Mobility 500 cm2/Vs
Hole Mobility 70 cm2/Vs

Thermal, Mechanical and Optical Properties

The thermal, mechanical and optical properties of boron phosphide are provided in the tables below:

Thermal Properties
Debye Temperature 707°C
Specific Heat Capacity 0.8 J/(gK)
Coefficient of Thermal Expansion 3.65×10-6/°C
Thermal Conductivity 4 W/cmK
Mechanical Properties
Density 2.90 g/cm3
Melting Point 1100°C
Knoop Microhardness 37000
Optical Properties
Refractive Index 3.1
Chromatic Dispersion -1.231 µm-1

Safety Information

Safety Information
GHS Hazard Statements H315 - Causes skin irritation
H319 - Causes serious eye irritation
H335 - May cause respiratory irritation.
Safety Precautions P261 - Avoid breathing dust/ fume/ gas/ mist/ vapors/ spray
P305 + P351 + P338 - If in eyes, rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.


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