Efficient Calculation of Quasi-bound States for the Simulation of Direct Tunneling

We study the calculation of quasi-bound states (QBS) in MOS inversion layers, which represent the major source of tunneling electrons. The calculation of QBS is performed by the perfectly matched layer (PML) method. Introducing a complex coordinate stretching enables us to apply artifical absorbing layers at the boundaries. This allows us to determine the QBS as the eigenvalues of a linear non-Hermitian Hamiltonian where the QBS lifetimes are directly related to the imaginary part of the eigenvalues. The PML formalism has been compared to other established methods and it has proven to be as an elegant, numerically stable, and efficient method to calculate QBS lifetimes.