 # Band structure and carrier concentration of Gallium Arsenide Antimonide (GaAsSb) ## Band structure and carrier concentration

Basic Parameters
Temperature Dependences
Dependence of the Energy Gap on Hydrostatic Pressure
Effective Masses
Donors and Acceptors

### Basic Parameters

 Energy gap 1.42-1.9x+1.2x2 (for 0 Band structure and carrier concentration of GaAs. 300 K Eg = 1.42 eV EL = 1.71 eV EX= 1.90 eV Eso = 0.34 eV Band structure and carrier concentration of GaSb. 300 K Eg= 0.726 eV EL = 0.81 eV EX = 1.03 eV Eso = 0.8 eV Variation of energy gap Eg with composition x for GaAs1-xSbx (Biryulin et al. (1979,a)).

#### For 0 < x < 0.3 at 300K:

Eg =1.42 - 1.9x + 1.2x2 Energy separation between L- valley of conduction band and top of the valence band (curve 1; Rosenbaum and Woolley (1975)) and energy gap (Curves 2-4; Taylor and Fortin (1970)) versus composition x. 2 - T=100 K, 3 - T=210 K, 1,4 -T=300 K.

### Temperature Dependences Temperature dependence of energy gap Eg for GaAs1-xSbx. 1 - x = 0.026, 2 - x = 0.05. ( Biryulin et al. (1979,b)).

#### For GaAs (x=0)

Eg=1.519-5.405·10-4·T2/(T+204) (eV),

#### For GaSb (x=1)

Eg = 0.813 - 3.78·10-4·T2(T+94) (eV),
where T is temperature in degrees K (0 < T < 300). The temperature dependences of the intrinsic carrier concentration. 1 - x=0 (GaAs), 2 - x=0.3, 3 - x=0.8, 4 - x=1 (GaSb) .

### Dependences on Hydrostatic Pressure

#### For GaAs (x=0)

Eg = Eg(0) + 0.0126·P - 3.77·10-5P2 (eV)
EL = EL(0) + 5.5·10-3P (eV)
EX = EX(0) + 1.5·10-3P (eV)

#### For GaSb (x=1)

Eg = Eg(0) + 14.5·10-3P (eV)
EL = EL(0) + 5.0·10-3P (eV)
EX = EX(0) - 1.5·10-3P (eV),
where P is pressure in kbar.

### Effective Masses

#### Electrons:

mΓ=(0.063 - 0.0495x + 0.0258x2)mo Dependence of electron effective mass m on composition parameter x. The curve is calculated. Dashed part of the curve corresponds to the miscibility gap. Symbols are experimental data taken from Delvin et al. (1981).

#### Holes:

 Heavy mh = (0.51 - 0.11x) mo Light mlp = (0.082 - 0.032x )mo Split-off band mso = 0.15 mo

### Donors and Acceptors

#### Ionization energies of shallow donors (meV)

 S Se Te x=0 (GaAs): 6 6 30 x=1 (GaSb): L 150 50 20 x=1 (GaSb): X 300 230 <80
For typical donor concentrations Nd≥1017 cm-3 the shallow donor states in GaSb connected with Γ - valley did not appear.

#### Ionization energies of shallow acceptors (meV)

 Si Zn Ge x=0 (GaAs): 30100220 25 30 x=1 (GaSb): 10 37 9
The dominant acceptor of undoped GaSb seems to be a native defect.
This acceptor is doubly ionizable: Ea1 =30, Ea2 =100.