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. Previous: III. Quantum Simulation of Up: III. Quantum Simulation of Next: 5. A Test Case