GaP - Gallium Phosphide

Electrical properties

Basic Parameters
Mobility and Hall Effect Transport Properties in High Electric Fields
Impact Ionization
Recombination Parameters

Basic Parameters

Breakdown field ≈1·106 V/cm
Mobility electrons ≤250 cm2 V-1s-1
Mobility holes ≤150 cm2 V-1s-1
Diffusion coefficient electrons ≤6.5 cm2/s
Diffusion coefficient holes ≤4 cm2/s
Electron thermal velocity 2·105 m/s
Hole thermal velocity 1.3·105m/s

Mobility and Hall Effect

Electron Hall mobility versus temperature for different donor (Sn) densities.
Nd (cm-3): 1. 5·1016; 2. 2·1017; 3. 2.5·1018; 4. 7.5·1018; 5. 1.2·1019.
(Kao and Eknoyan [1983]).
Electron Hall mobility versus donor (Sn) density at different temperature.
T (K): 1. 203; 2. 233; 3. 273; 4. 300; 5. 400; 6. 500.
For T>200 K electron Hall mobility µnH~T-1.7
(Kao and Eknoyan [1983]).
Electron Hall mobility versus temperature for different acceptor (Zn) densities.
Na (cm-3): 1. 6.7·1016; 2. 1.9·1017; 3. 6.7·1017; 4. 3.8·1018; 5. 1.2·1019.
(Casey et al. [1969]).
Hole Hall mobility versus temperature for different acceptor (Mg) densities.
Na (cm-3): 1. 5·1016; 2. 3·1017; 3. 6·1017; 4. 1·1018; 5. 2·1018.
(Kao and Eknoyan [1983]).
Hole Hall mobility versus acceptor (Mg) density at different temperature.
T (K): 1. 203; 2. 233; 3. 300; 4. 350; 5. 400; 6. 500.
For T>200 K hole Hall mobility µpH~T-2.3
(Kao and Eknoyan [1983]).
Hole concentration versus temperature for different acceptor (Zn) densities.
Na (cm-3): 1. 6.7·1016; 2. 6.7·1017; 3. 3.8·1018; 4. 1.2·1019; 5. 2.1·1019.
(Casey et al. [1969]).

Transport Properties in High Electric Fields

Field dependences of the electron drift velocity 300 K.
Solid line shows the result of the calculation.
Dashed line shows the experimental results
(Arora et al. [1987]).

Saturation electron drift velocity

vs = 1.25·107 cm/s (300 K)
(Johnson and Eknoyan [1985])

Impact Ionization

The dependence of ionization rates for electrons αi and holes βi versus electric field, 300 K.
αi= βi
(Sze [1969]).
At 300 K for 5·105 V/cm < F < 1.3·106 V/cm
αi = β i = αo·exp(δ - (δ2 + (Fo/F)2)1/2,
where αo = 0.39·106 cm-1, δ=19.1, Fo=7.51·106 V cm-1
(Kyuregyan and Yurkov [1989]).
Breakdown voltage and breakdown field versus doping density for an abrupt p-n junction, 300 K
(Sze and Fibbons [1966]).

Recombination Parameters

Hole diffusion length Lp in n-type GaP (undoped or doped with S) versus donor density, 300 K
(Young and Wight [1974]).
Electron diffusion length Ln in p-type GaP versus acceptor (Zn) density, 300 K
(Young and Wight [1974]).
The longest lifetime of holes (undoped GaP) τp ~ 1·10-6 s
Diffusion length Lp = (Dp·τp)1/2 Lp ~ 20 µm.
The longest lifetime of electrons τn ~ 1·10-7 s
Diffusion length Ln = (Dn·τn)1/2 Ln ~ 7 µm
Surface recombination
(Gershenzon and Mikulyak [1966])
20 K
 (0.1 ÷ 3.4)·102 cm/s
77 K
 (1.1 ÷ 90)·104 cm/s
300 K
 (0.4 ÷ 2)·106 cm/s
Radiative recombination
Band to band radiative recombination coefficient - 10-13 cm3/s
Impurity recombination at 300 K
(Yunovich [1972], Bergh and Dean[1976])		  
Zn-O complex (red LED, hν≈1.8 eV, λ≈0.7 µm)
Radiative exciton lifetime
 ~10-7 s-1
Oscillator force for exciton recombination
 0.07
Non - radiative exciton lifetime:
τxn=1/B·p
 B≈10-10 ÷- 10-11 cm3/s
Non - radiative single electron lifetime: τcn=1/C·p2
 C≈10-30 cm6/s
N - isoelectron impurity (green LED, hν~2.22 eV, λ~0.56 µm)
Radiative exciton lifetime
 - 3·10-8 s
Oscillator force for exciton recombination
 0.09
Bond energy of exciton in GaP doped with N:

free exciton

 0.021 eV

N N bound exciton

 0.143 eV
Auger recombination coefficient - 10-30 cm6/s