GaN

Gallium Nitride (GaN) is a very hard, mechanically stable, wide bandgap semiconductor. GaN is used in light emitting diodes, lasers, sensors, high-power transistors, and high-frequency transistors. Gallium Nitride forms the wurtzite and zincblende crystal structures.


Crystal structure: Wurtzite
Bravais lattice: hexagonal
Space group: P63mc = 186
Point group: 6mm = C6v
Molecular Weight 83.73 g/mol
Molecular density natoms=8.9×1022 1/cm³ 
Density ρ=6.15 g/cm³

The primitive GaN wurtzite unit cell contains 4 atoms.

The N atoms are positioned at [13,23,0] and [23,13,12] while the Ga atoms are positioned at [13,23,38] and [23,13,78].

The lattice parameters of the conventional unit cell are:

a=0.3180nm,b=0.3180nm,c=0.5166nm,α=90,β=90,γ=120.

Wurtzite and Zincblende comparison

Properties

Wurtzite

Zincblende

Bandgap Eg

3.4 eV (direct)

3.2 eV (direct)

Effective density of states in conduction band (300 K) Nc

2.3 × 1024 m-3

1.2 × 1024 m-3

Effective density of states in valence band (300 K) Nv

4.6 × 1025 m-3

4.1 × 1025 m-3

Effective mass electrons
m*/m0

m* = 0.20

m* = 0.13

Effective mass holes
m*/m0

mlh* = 0.3
mhh* =1.4

mlh* = 0.19
mhh* = 1.3

Electric Breakdown Field

3.3 × 106 V/cm


Electrical Band Structure (Wurtzite)

GaN is a direct bandgap semiconductor.


Source: Rheinlander, A., Neumann, H. Plasma Faraday Rotation in n-Type GaN. Phys. Status Solidi (b) 64 (1974) K123.
https://onlinelibrary.wiley.com/toc/15213951/64/2 (1 August 1974) Accessed: 01-02-2021