Database for wurtzite materials (hexagonal
crystal system)
=> ../Syntax/database_nnp.in
Group IV, III-V, II-VI, I-VII materials
binary_wz {
name = GaN
# material name, e.g. GaN,
AlN, InN, ...
valence = III_V
# IV_IV for group IV materials (like SiC,
...)
# III_V for III-V materials (like GaN, AlN,
...)
# II_VI for II-VI materials (like ZnO,
...)
# I_VII for I-VII materials (like CuCl, ...)
lattice_consts{
a =
3.189 # [Angstrom] lattice constant at 300
K (perpendicular to hexagonal c axis)
#
a_expansion = 5.59e-5
# [Angstrom/K] The lattice constants are temperature dependent => a(T).
c =
5.185 # [Angstrom]
c_expansion = 3.17e-5
# [Angstrom/K] =>
c(T).
# The lattice constants a and c in the
database should be given for 300 K.
# For all other temperatures, the lattice
constants are calculated by the following formula
# where T is the temperatue in units of [K]:
# a(T) = a(300 K) + a_expansion * (T - 300 K)
# c(T) = c(300 K) + c_expansion * (T - 300 K)
# The lattice constants are needed for the
calculation of the strain.
}
dielectric_consts{
static_a = 9.28
# [-] static or low frequency (epsilon(omega=0)) dielectric
constant (perpendicular to hexagonal c axis)
static_c = 10.01
# [-] epsilon(omega=0)) dielectric
constant (along hexagonal c axis)
optical_a = 5.29 #
[-]
optical_c = 5.29 #
[-]
#
# The static dielectric constants enter the Poisson
equation.
# They are also needed to calculate the optical
absorption and enter the equation for the exciton correction.
}
elastic_consts{
c11 = 390
# [GPa] elastic constants
c12 = 145
# -> 39.0
* 1011 dyn/cm2
= 390 GPa
c13 = 106
#
c33 = 398
#
c44 = 105
# The elastic constants are needed for the
calculation of the strain in heterostructures.
}
piezoelectric_consts{
e31 = -0.35 # [C/m2] piezoelectric constants
e33 = 1.27 #
e15 = -0.30 #
B311 = 0.0
# [C/m2]
B312 = 0.0
# [C/m2] 2nd order piezoelectric constant (optional)
B313 = 0.0
# [C/m2] 2nd order piezoelectric constant (optional)
B333 = 0.0
# [C/m2] 2nd order piezoelectric constant (optional)
B115 = 0.0
# [C/m2] 2nd order piezoelectric constant (optional)
B125 = 0.0
# [C/m2] 2nd order piezoelectric constant (optional)
B135 = 0.0
# [C/m2] 2nd order piezoelectric constant (optional)
B344 = 0.0
# [C/m2] 2nd order piezoelectric constant (optional)
}
pyroelectric_consts{ p1 = -0.034 }
# [C/m2] pyroelectric constant (spontaneous polarization)
#
conduction_bands{
Gamma{
# material parameters for the conduction band valley at the Gamma point
of the Brillouin zone
mass_t
= 0.202 # [m0]
mass_l
= 0.206 # [m0]
#
bandgap =
3.510 # [eV]
bandgap_alpha = 0.909e-3
# [eV/K] alpha for temperature dependent
band gap
bandgap_beta = 830
# [K] beta for
temperature dependent band gap
#
absolute deformation potentials of Gamma conduction band minima
ac,a=a2 (a axis),
ac,a=a2 (a axis), ac,c=a1 (c
axis)
defpot_absolute_t = -11.3
# [eV] absolute deformation potential of the
Gamma conduction band perpendicular to hexagonal c axis ac,a=a2
defpot_absolute_l = -4.9
# [eV] absolute deformation potential of the Gamma
conduction band along hexagonal c axis ac,c=a1
# Note that I. Vurgaftman et al., JAP 94, 3675 (2003) lists
a1 and a2
parameters.
#
They refer to the interband deformation potentials, i.e. to the
deformation of the band gaps.
#
Thus we have to add the deformation potentials of the valence bands to get
the deformation potentials for the conduction band edge.
# ac,a = a2
=
a2 + D2
# ac,c = a1
=
a1 + D1
g_t
= 0
# [] g factor perpendicular to hexagonal
c axis (for Zeeman splitting in magnetic fields)
g_l
= 0
# []
}
}
valence_bands{
# material parameters for the valence band valley at the Gamma point of
the Brillouin zone
bandoffset = -0.726
#
#
Note: This energy determines the valence band offset (VBO) between two
materials
#
VBOv,av =
bandoffset(material1) - bandoffset(material2)
#
The average of the three holes in wurtzite is defined as:
bandoffset = Ev,av
= (Ehh + Elh + Ech ) / 3 - 2/3 Deltacr
#
For comparison, in zinc blende this reads:
bandoffset = Ev,av
= (Ehh + Elh + Eso ) / 3
#
The "average" valence band edge energy in wurtzite is according to Ev
in:
#
S.L. Chuang, C.S. Chang
#
k.p method for strained wurtzite semiconductors
#
Phys. Rev. B 54 (4), 2491 (1996)
#
#
defining an "average" valence band energy Ev (=Ev,av) for all three bands and adding the
spin-orbit-splitting and
#
#
The "average" valence band energy Ev (=Ev,av) is defined on an absolute
energy scale and must take into accout the
#
valence band offsets which are "averaged" over the three holes.
HH{ mass_t = 1.6
# [m0]
heavy hole effective mass perpendicular to hexagonal c axis (parabolic !)
mass_l = 1.1
# [m0]
g_t = 0
# []
g_l = 0
# []
LH{ mass_t = 0.15 # [m0]
mass_l = 1.1 # [m0]
g_t = 0
# []
g_l = 0
# []
SO{ mass_t = 1.1 # [m0]
mass_l = 0.15 # [m0]
g_t = 0
# []
g_l = 0
# []
#
defpotentials = [ -3.7 , # [eV] D1
4.5 , # [eV] D2
8.2 , # [eV] D3
-4.1 , # [eV] D4
-4.0 , # [eV] D5
-5.5 ]
# [eV] D6
delta =
[ 0.010 , # [eV] crystal-field splitting energy Deltacr = Delta1
0.00567 , # [eV] spin-orbit splitting energy
parameter Delta2
0.00567 ]
# [eV] spin-orbit splitting energy parameter Delta3
}
# Very often one assumes Delta2
= Delta3 = 1/3 Deltaso.
kp_6_bands{
#
A1 = -7.21
# [-] A1
A2 = -0.44
# [-] 6-band k.p hole effective mass parameter A2
A3 = 6.68
# [-] 6-band k.p hole effective mass parameter A3
A4 = -3.46
# [-] 6-band k.p hole effective mass parameter A4
A5 = -3.40
# [-] 6-band k.p hole effective mass parameter A5
A6 = -4.90
# [-] 6-band k.p hole effective mass parameter A6
}
kp_8_bands{
S1 = 0.866 S2
= 0.962 # [-] electron effective mass parameter S1=Sparallel and S2=Sperp. for 8-band
k.p
E_P1 = 14.0 E_P2 =
14.0 # [eV] Ep1=Ep,parallel, Ep2=Ep,perp.
# Note: The momentum matrix element parameter P is related
to Ep: P2
= hbar2/(2m0) Ep
# The units of P are
[eV Angstrom].
B1 = 0.0937
B2 = 0.0937
# [hbar2/(2m0)] bulk
inversion symmetry parameters B1, B2,
B3 (sometimes also called A7)
B3 = 0.0937
#
A1 = -3.221
# [-] A1'
(Rashba-Sheka-Pikus parameter)
A2 = -0.44
# [-] 8-band k.p hole effective mass parameter A2'
(Rashba-Sheka-Pikus parameter)
A3 = 2.691
# [-] A3'
(Rashba-Sheka-Pikus parameter)
A4 = -1.466
# [-] A4'
(Rashba-Sheka-Pikus parameter)
A5 = -1.406
# [-] A5'
(Rashba-Sheka-Pikus parameter)
A6 = -2.080
# [-] A6'
(Rashba-Sheka-Pikus parameter)
}
mobility_constant{...}
#
mobility_masetti{...}
#
mobility_arora{...}
#
mobility_minimos{...}
#
mobility_simba{...}
#
recombination{
SRH
{...}
#
Auger {...}
#
radiative{...}
#
}
} : {
name = galliumn_nitride
# "GaN" and "galliumn_nitride" are
synonyms for the same set of material parameters.
valence = III_V
}
} : {
name = "galliumn nitride"
# It is possible to define a synonym or several synonyms for this
material. Here: "GaN" and "galliumn nitride" are
synonyms for the same set of material parameters.
valence = III_V
}
The deformation potentials are only used if strain is
present. They enter the k.p equations. If the single-band approximation
is used, the deformation potentials are used to shift and split the conduction
and valence band edges.
The g factors (g_t, g_l)
are optional. If the g factors are specified in the input file, the database
value for the g factors are overwritten with the value in the input file. If no
g factors are present in the input file or in the database, a g factor of 2 is
assumed by default.
ternary_wz{
...
Analogously to the zincblende
case. Please check the appropriate secion there.
}
ternary2_wz{
...
Analogously to the zincblende
case. Please check the appropriate secion there.
}
########################### QUINTERNARY WURTZITE ##########################
is analogous
with _wz instead of _zb ...
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