To specify the properties of impurities used in the simulation.
integer_array required !
impurity-number = integernumber, 1 or 2 ... (impurity numbers labeled in doping-function)
A unique integer number as usual.
impurity-name = charactera name (for later use - planned to read parameters
An arbitrary name - currently not in use.
impurity-type = n-typeSpecifies the type of an impurity.
means, that the
impurity is treated as a donor,
p-type as an acceptor.
trap is not supported so far.
number-of-energy-levels = integer
number of different energy levels of this impurity
energy-levels-relative = energy1
in units of
[eV]a large negative value implies full ionization
0.054d0 ! n-As-in-SiMore parameters can be found in the database file
0.045d0 ! n-P
0.039d0 ! n-Sb-in-Si
0.045d0 ! n-N
0.006d0 ! n-Si-in-Al0.27Ga0.73As
0.0058d0 ! n-Si-in-GaAs
0.007d0 ! n-Si-in-AlAs
0.10d0 ! n-N
= 0.20d0 !
= 0.045d0 !
= 0.16d0 !
0.027d0 ! p-C -in-GaAs
database_nn3.in or at this website:
Energy levels relative to 'nearest'
band edge (
n-type -> conduction band, else valence band)
in units of [eV].
As many energies as energy levels. These energies are meant as ionization
energies, e.g. a donor with an energy level right below the conduction
band edge would be specified by a small positive energy level.
When impurity levels are relatively deep compared to the thermal energy kBT/e
at room temperature, incomplete ionization must be considered.
energy-levels-relative = -1000d0
(e.g.), that means, all electrons are fully ionized from
the donors (similar for holes/acceptors). This might be useful for low temperatures like 4
K where usually the degree of ionization is very small. By using
one can force them to be completely ionized.)
The energy levels of the donors and acceptors relative to the lowest conduction
band edge and highest valence band edge can be output using
dopant-energy-levels = yes
See also our tutorial on
semiconductors to learn more about partial ionization.
degeneracy-of-energy-levels = deg1 deg2 ...
2 ! n-type
4 ! p-type
Degeneracy of the specified energy levels
shallow donors: degeneracy factor 2
Outer s orbital is onefold occupied (neutral state). There is one
possibility to get rid of one electron but there are two to incorporate
one (spin up, spin down).
shallow acceptors: degeneracy factor 4
The sp3 orbital is threefold occupied. Thus, one possibility
to incorporate an electron, four possibilities to get rid of one.
More details on degenerate impurity levels can be found in e.g. "Physics of
Optoelectronic Devices" by Shun L. Chuang.
Note that in nitride semiconductors crystallizing in the wurtzite structure the
degeneracy factor may vary from 4 to 6 because of a small valence
If full ionization is assumed, i.e.
-1000d0, then the degeneracy factor
effectively becomes irrelevant. This can be seen from eqs. (1.4) - (1.7) in PhD
thesis of S. Birner.
transition-times-cb-to-levels = tau1 tau2 ...
Transition times from conduction band(s) to energy levels
required in case of
trap: times from conduction band to discrete
transition-times-levels-to-vb = tau1 tau2 ...
Transition times from energy levels to valence band(s)
required in case of
trap: times from discrete levels to valence
Note: Currently no interlevel transition times implemented. Can be
added provided there are also models which can handle such things.