def test_effective_mass():
"""Test calculation of valence band masses from Luttinger parameters."""
matlib = materials.Materials()
gasb = matlib['GaSb']
# check basic mass anisotropy
assert gasb.holeMass('heavy', 'z') == gasb.holeMass('heavy', '001')
assert gasb.holeMass('heavy', '001') < gasb.holeMass('heavy', '110')
assert gasb.holeMass('heavy', '110') < gasb.holeMass('heavy', '111')
assert gasb.holeMass('light', 'z') == gasb.holeMass('light', '001')
assert gasb.holeMass('light', '001') > gasb.holeMass('light', '110')
assert gasb.holeMass('light', '110') > gasb.holeMass('light', '111')
# compare DOS average masses to directional masses
assert gasb.holeMass('heavy', '001') < gasb.holeMass('heavy', 'dos') < \
gasb.holeMass('heavy', '110')
assert gasb.holeMass('light', '001') > gasb.holeMass('light', 'dos') > \
gasb.holeMass('light', '110')
assert gasb.holeMass('light', 'dos') < gasb.holeMass('heavy', 'dos') < \
gasb.holeMass('dos', 'dos')
# compare to a few reference values from http://www.ioffe.ru/SVA/NSM/
assert gasb.holeMass('heavy', 'dos') == approx(0.4, rel=0.2)
assert gasb.holeMass('light', 'dos') == approx(0.05, rel=0.2)
inas = matlib.find('InAs')
inas.holeMass('heavy', 'dos')
assert inas.holeMass('heavy', 'dos') == approx(0.41, rel=0.2)
assert inas.holeMass('light', 'dos') == approx(0.026, rel=0.2)
assert inas.holeMass('dos', 'dos') == approx(0.41, rel=0.2)
def test_bowing_parameters():
"""Test calculation of alloy band positions with bowing parameters."""
matlib = materials.Materials()
inas = matlib.find('InAs', eunit='meV')
insb = matlib.find('InSb', eunit='meV')
alloy = matlib.find('InAs80Sb20', eunit='meV')
# band gap bowing for InAsSb is strong enough to push CBM in alloy below
# CBM in either binary
assert matlib.conductionBandMinimum(alloy) < matlib.conductionBandMinimum(
inas)
assert matlib.conductionBandMinimum(inas) < matlib.conductionBandMinimum(
insb)
# check that we have bowing parameters for m_* and E_g, which are
# significant for this alloy
bow = matlib.bowingParameters[('InAs', 'InSb')]
assert 'directBandGap' in bow and 'electronMass' in bow
# check interpolation with bowing parameters
x = 0.2
gap = (1 - x) * inas['directBandGap'] + x * insb['directBandGap'] \
- x * (1 - x) * bow['directBandGap']
mass = (1 - x) * inas['electronMass'] + x * insb['electronMass'] \
- x * (1 - x) * bow['electronMass']
assert alloy['directBandGap'] == approx(gap)
assert alloy['electronMass'] == approx(mass)
# parameters for which we don't have bowing parameters should be linearly
# interpolated
assert 'valenceBandOffset' not in bow
vbo = (1 - x) * inas['valenceBandOffset'] + x * insb['valenceBandOffset']
assert alloy['valenceBandOffset'] == approx(vbo)
def test_band_offsets_fallback():
"""Test calculation of band positions and offsets via fallback on Anderson's rule."""
# define a couple of semiconductors without valenceBandOffset
matlib = materials.Materials()
matlib.add_material("GaAs",
"semi",
electronAffinity=4070.0,
directBandGap=1519.0)
matlib.add_material("InAs",
"semi",
directBandGap=417.0,
electronAffinity=4900.0)
matlib.add_material("InSb",
"semi",
electronAffinity=4590.0,
directBandGap=235.0)
mat1 = matlib.find("InSb", eunit="eV")
mat2 = matlib.find("InAs", eunit="eV")
mat3 = matlib.find("GaAs", eunit="eV")
assert matlib.conduction_band_minimum(
mat1) - mat1["directBandGap"] == approx(
matlib.valence_band_maximum(mat1))
assert matlib.conduction_band_minimum(
mat1) - matlib.conduction_band_minimum(mat2) == approx(
materials.conduction_band_offset(mat1, mat2))
assert matlib.valence_band_maximum(mat1) + mat1["directBandGap"] == approx(
matlib.conduction_band_minimum(mat1))
assert matlib.valence_band_maximum(mat1) - matlib.valence_band_maximum(
mat2) == approx(materials.valence_band_offset(mat1, mat2))
assert materials.conduction_band_offset(
mat1, mat2) + materials.conduction_band_offset(mat2, mat3) == approx(
materials.conduction_band_offset(mat1, mat3))
assert materials.valence_band_offset(
mat1, mat2) + materials.valence_band_offset(mat2, mat3) == approx(
materials.valence_band_offset(mat1, mat3))
def test_bowing_parameters():
"""Test calculation of alloy band positions with bowing parameters."""
matlib = materials.Materials()
inas = matlib.find("InAs", eunit="meV")
insb = matlib.find("InSb", eunit="meV")
alloy = matlib.find("InAs80Sb20", eunit="meV")
# band gap bowing for InAsSb is strong enough to push CBM in alloy below
# CBM in either binary
assert matlib.conduction_band_minimum(
alloy) < matlib.conduction_band_minimum(inas)
assert matlib.conduction_band_minimum(
inas) < matlib.conduction_band_minimum(insb)
# check that we have bowing parameters for m_* and E_g, which are
# significant for this alloy
bow = matlib.bowingParameters[("InAs", "InSb")]
assert "directBandGap" in bow and "electronMass" in bow
# check interpolation with bowing parameters
x = 0.2
gap = ((1 - x) * inas["directBandGap"] + x * insb["directBandGap"] - x *
(1 - x) * bow["directBandGap"])
mass = ((1 - x) * inas["electronMass"] + x * insb["electronMass"] - x *
(1 - x) * bow["electronMass"])
assert alloy["directBandGap"] == approx(gap)
assert alloy["electronMass"] == approx(mass)
# parameters for which we don't have bowing parameters should be linearly
# interpolated
assert "valenceBandOffset" not in bow
vbo = (1 - x) * inas["valenceBandOffset"] + x * insb["valenceBandOffset"]
assert alloy["valenceBandOffset"] == approx(vbo)
def test_effective_mass():
"""Test calculation of valence band masses from Luttinger parameters."""
matlib = materials.Materials()
gasb = matlib["GaSb"]
# check basic mass anisotropy
assert gasb.hole_mass("heavy", "z") == gasb.hole_mass("heavy", "001")
assert gasb.hole_mass("heavy", "001") < gasb.hole_mass("heavy", "110")
assert gasb.hole_mass("heavy", "110") < gasb.hole_mass("heavy", "111")
assert gasb.hole_mass("light", "z") == gasb.hole_mass("light", "001")
assert gasb.hole_mass("light", "001") > gasb.hole_mass("light", "110")
assert gasb.hole_mass("light", "110") > gasb.hole_mass("light", "111")
# compare DOS average masses to directional masses
assert (gasb.hole_mass("heavy", "001") < gasb.hole_mass("heavy", "dos") <
gasb.hole_mass("heavy", "110"))
assert (gasb.hole_mass("light", "001") > gasb.hole_mass("light", "dos") >
gasb.hole_mass("light", "110"))
assert (gasb.hole_mass("light", "dos") < gasb.hole_mass("heavy", "dos") <
gasb.hole_mass("dos", "dos"))
# compare to a few reference values from http://www.ioffe.ru/SVA/NSM/
assert gasb.hole_mass("heavy", "dos") == approx(0.4, rel=0.2)
assert gasb.hole_mass("light", "dos") == approx(0.05, rel=0.2)
inas = matlib.find("InAs")
inas.hole_mass("heavy", "dos")
assert inas.hole_mass("heavy", "dos") == approx(0.41, rel=0.2)
assert inas.hole_mass("light", "dos") == approx(0.026, rel=0.2)
assert inas.hole_mass("dos", "dos") == approx(0.41, rel=0.2)
def test_band_offsets_fallback():
"""Test calculation of band positions and offsets via fallback on Anderson's rule."""
# define a couple of semiconductors without valenceBandOffset
matlib = materials.Materials()
matlib.add_material('GaAs',
'semi',
electronAffinity=4070.,
directBandGap=1519.)
matlib.add_material('InAs',
'semi',
directBandGap=417.,
electronAffinity=4900.)
matlib.add_material('InSb',
'semi',
electronAffinity=4590.,
directBandGap=235.)
mat1 = matlib.find('InSb', eunit='eV')
mat2 = matlib.find('InAs', eunit='eV')
mat3 = matlib.find('GaAs', eunit='eV')
assert matlib.conduction_band_minimum(mat1) - mat1['directBandGap'] == \
approx(matlib.valence_band_maximum(mat1))
assert matlib.conduction_band_minimum(
mat1) - matlib.conduction_band_minimum(mat2) == approx(
materials.conduction_band_offset(mat1, mat2))
assert matlib.valence_band_maximum(mat1) + mat1['directBandGap'] == \
approx(matlib.conduction_band_minimum(mat1))
assert matlib.valence_band_maximum(mat1) - matlib.valence_band_maximum(
mat2) == approx(materials.valence_band_offset(mat1, mat2))
assert materials.conduction_band_offset(mat1, mat2) + \
materials.conduction_band_offset(mat2, mat3) == \
approx(materials.conduction_band_offset(mat1, mat3))
assert materials.valence_band_offset(mat1, mat2) + \
materials.valence_band_offset(mat2, mat3) == \
approx(materials.valence_band_offset(mat1, mat3))
def test_band_offsets():
"""Test calculation of band positions and offsets."""
matlib = materials.Materials()
mat1 = matlib.find("InSb", eunit="eV")
mat2 = matlib.find("InAs", eunit="eV")
mat3 = matlib.find("GaAs", eunit="eV")
assert matlib.conduction_band_minimum(mat1) - mat1["directBandGap"] == approx(
matlib.valence_band_maximum(mat1)
)
assert matlib.conduction_band_minimum(mat1) - matlib.conduction_band_minimum(
mat2
) == approx(materials.conduction_band_offset(mat1, mat2))
assert matlib.valence_band_maximum(mat1) + mat1["directBandGap"] == approx(
matlib.conduction_band_minimum(mat1)
)
assert matlib.valence_band_maximum(mat1) - matlib.valence_band_maximum(
mat2
) == approx(materials.valence_band_offset(mat1, mat2))
assert materials.conduction_band_offset(
mat1, mat2
) + materials.conduction_band_offset(mat2, mat3) == approx(
materials.conduction_band_offset(mat1, mat3)
)
assert materials.valence_band_offset(mat1, mat2) + materials.valence_band_offset(
mat2, mat3
) == approx(materials.valence_band_offset(mat1, mat3))
def test_band_offsets():
"""Test calculation of band positions and offsets."""
matlib = materials.Materials()
mat1 = matlib.find('InSb', eunit='eV')
mat2 = matlib.find('InAs', eunit='eV')
mat3 = matlib.find('GaAs', eunit='eV')
assert matlib.conductionBandMinimum(mat1) - mat1['directBandGap'] == \
approx(matlib.valenceBandMaximum(mat1))
assert matlib.conductionBandMinimum(mat1) - matlib.conductionBandMinimum(
mat2) == approx(materials.conduction_band_offset(mat1, mat2))
assert matlib.valenceBandMaximum(mat1) + mat1['directBandGap'] == \
approx(matlib.conductionBandMinimum(mat1))
assert matlib.valenceBandMaximum(mat1) - matlib.valenceBandMaximum(
mat2) == approx(materials.valence_band_offset(mat1, mat2))
assert materials.conduction_band_offset(mat1, mat2) + \
materials.conduction_band_offset(mat2, mat3) == \
approx(materials.conduction_band_offset(mat1, mat3))
assert materials.valence_band_offset(mat1, mat2) + \
materials.valence_band_offset(mat2, mat3) == \
approx(materials.valence_band_offset(mat1, mat3))