Any new technology must extend microelectronics well beyond the domain of CMOS and should be interface-able with a CMOS platform [HBZB02], [RO001]. One candidate to complement CMOS in the long-term run is resonant tunneling with the use of RTD-FETs as novel logic devices. RTD device technology is now quite mature with many demonstrations of circuits [CMP03]. These are the first quantum transport devices to have made it into (pilot) production.

We see the simulation of RTDs as a test case for the simulation of quantum transport as is also needed for novel CMOS technology. Channel lengths or silicon films of a few nanometers cannot be accurately represented without (partially) ballistic transport models which also include quantum effects [BJSS04], [HWL04].

In scaled CMOS technology the short distance between
source and drain requires a full two-dimensional
quantum transport formulation [HWL04].
Several approaches have
been suggested to realize these calculations.
The simplest scheme is based on a self-consistent
Poisson-Schrödinger coupled set of equations. A more
advanced method is the quantum Liouville equation
formulated in the Wigner function or in moments of
the Wigner function leading to a quantum drift-diffusion
model. Apart from the formal justification of the
computational algorithm the CPU demands are also huge.
These simulation methods were compared using the
one-dimensional RTD as a testbed, where simulation costs
are feasible.
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R. Kosik: Numerical Challenges on the Road to NanoTCAD