The following page (in construction) describes the simulation of devices with open boundary conditions such as RTDs with the nextnano.NEGF software.
Note that in the current version (2022-03-30), only single band calculations are supported for open boundary conditions. A multiband version is currently developed.
In order to simulate a system with open boundary conditions (instead of the default field-periodic boundary condition), contacts have to be defined by adding a <Contacts>
section in the input file:
<Contacts> <DensityLeft unit="cm^-3">1e18</DensityLeft> <DensityRight unit="cm^-3">1e18</DensityRight> <MaterialLeft>well</MaterialLeft> <MaterialRight>well</MaterialRight> <Broadening unit="meV">10.0</Broadening> <Ballistic>no</Ballistic> </Contacts>
In this section, the carrier densities in the left and right contact have to been defined using the <DensityLeft>
and <DensityRight>
commands, as shown above. The unit is cm$^{-3}$.
The material of the left and right contacts needs to be defined by te command <MaterialLeft>
and <MaterialRight>
. The string value has to be an alias defined in the <Materials>
section of the input file.
A broadening energy can be defined by the command <Broadening>
. Indeed, scattering is not accounted in the contact, so that this commands allows a phenomenological broadening of the density of states in the contact.
The command <Ballistic>
can be used to calculate ballistic transport between the contacts (i.e. no scattering process considered) if its value is set to yes
.
The tutorial for AlGaAs/GaAs intraband RTD is available on our new manual from here.