Band structure and carrier concentration of Gallium Phosphide (GaP)

Band structure and carrier concentration
Basic ParametersTemperature Dependences
Dependences on Hydrostatic Pressure
Energy Gap Narrowing at High Doping Levels
Effective Masses
Donors and Acceptors
Basic Parameters
Energy gap | 2.26 eV |
Energy separation Eo (Γ1c - Γ15ν) | 2.78 eV |
Energy spin-orbital splitting | 0.08 eV |
Intrinsic carrier concentration | 2 cm-3 |
Effective conduction band density of states | 1.8·1019 cm-3 |
Effective valence band density of states | 1.9·1019 cm-3 |
![]() |
Band structure and carrier concentration of GaP. Important minima of the conduction band and maxima of the valence band. 300 K Eg = 2.26 eV EL = 2.6 eV Eo = 2.78 eV Eso = 0.08 eV |
Temperature Dependences
Temperature dependence of the direct energy gap.
Eg=2.34-6.10-4·[T2/(T+460)] (eV),where T is temperature in degrees K (0 < T < 1200),
(Panish and Casey [1969]).
Temperature dependence of the direct band gap Eo
Eo=2.866-0.108·[coth(164/T)-1] (eV),where T is temperature in degrees K (0 < T < 300),
(Takizawa [1983]).
Effective density of states in the conduction band
Nc≈3.4·1015·T3/2 (cm-3)Effective density of states in the valence band
Nn≈3.6·1015·T3/2 (cm-3)![]() |
The temperature dependence of the intrinsic carrier concentration. |
![]() |
Fermi level versus temperature for different concentrations of shallow donors and acceptors. |
Dependences on Hydrostatic Pressure

where P is pressure in kbar;
(Ves et al. [1985]).
Energy Gap Narrowing at High Doping Levels
![]() |
Energy gap narrowing versus donor (curve 1) and acceptor (curve 2) doping density, T= 300 K, (calculated according Jain et al. [1990]). |
For n-type GaP
ΔEg = 10.7·10-9·Nd1/3 + 3.45·10-7·Nd1/4 + 9.97·10-12·Nd1/2 (eV)(Jain et al. [1990]).
For p-type GaP:
ΔEg = 12.7·10-9·Na1/3 + 5.85·10-7·Na1/4 +3.90·10-12·Na1/2 (eV)(Jain et al. [1990]).
Effective Masses
Electrons: | |
The surfaces of equal energy are ellipsoids (X-valley) | |
ml = 1.12mo | |
mt = 0.22mo | |
Effective mass of density of states | |
mc=(9mlmt2)1/3 | mc=0.79mo |
Effective mass of conductivity | mcc=0.35mo |
For Γ-valley | mΓ = 0.09mo |
For L-valley | ml = 1.2mo |
mt = 0.15mo | |
Holes: | |
Heavy | mh = 0.79mo |
Light | mlp = 0.14mo |
Effective mass of density of states | mv = 0.83mo |
Donors and Acceptors
Ionization energies of shallow donors (eV)
Sp | Sep | Tep | Lip | GeGa | SiGa | SnGa | LiGa |
0.107 | 0.105 | 0.093 | 0.091 | 0.204 | 0.085 | 0.072 | 0.061 |
Ionization energies of shallow acceptors (eV)
Gep | Cp | Sip | BeGa | CdGa | MgGa | ZnGa |
0.265 | 0.0543 | 0.210 | 0.0566 | 0.1022 | 0.0599 | 0.0697 |
Most important deep levels
Impurity | Position in the forbidden gap |
Op(donor) | Ec - 0.89 (eV) |
Cr (acceptor) | Ec - 1.2 (eV) |
Ec - 0.5 (eV) | |
Radiative centers(Baegh and Dean[1976]) | |
N | Ev + 0.008 (eV) |
ZnGa - Op | Ec - 0.3 (eV) |
Capture cross section for electrons to neutral Zn-O complex (at 300 K) | σn~(1.5÷4.5)·10-16 (cm2) |
Capture cross section for holes to negative Zn-O complex (at 77 K): | σp ~ 5·10-17 (cm2 |
CdGa - Op | Ec - 0.40 (eV) |
Mg - O | Ec - 0.14 (eV) |