Two-dimensional modeling of the MIS grating solar cell

A two-dimensional model has been developed for simulating the behavior of a metal-insulator-semiconductor (MIS) grating solar cell. In contrast with traditional methods, which solve the nonlinear semiconductor equations directly, this model solves a derived nonlinear boundary value problem, using an integral equation technique. The general characteristics of MIS grating solar cells have been calculated and are explained in terms of the underlying physical processes. In order to gain a better understanding of the collection mechanism taking place in a grating solar cell, a new concept, the "diffusion thickness of the space-charge layer" is introduced. The best-known grating solar cell is the MIS inversion layer solar cell. However, it is shown that for common values of the surface charge, an inversion layer cell with a low base doping level may not have as high an efficiency as a cell with a more heavily doped base, in which the minority-carrier flow is two-dimensional.