OPTICALLY INDUCED SWITCHING IN BISTABLE STRUCTURES: HEAVILY DOPED n~+- POLYSILICON - TUNNEL OXIDE LAYER - n - SILICON

摘要

1. The presence of a n~+ -polysilicon electrode instead of a metal electrode gives additional specific features. For example, on the steady-state non-equilibrium depletion regime the bandgap in the gate electrode material blocks virtually completely the current transport channel associated with transfer of minority carriers (holes) from the valence band in n-Si into the gate material via surface states on the n-Si-SiO_2 interface (Fig.3a). For this reason, in the case of a polycrystalline silicon electrode the condition E_(Fm) -E_c (0) > 0 is more easily satisfied in the steady-state non-equilibrium depletion regime than in the case of a metal electrode [7]. A similar situation obtains in the "on" state: The lower the hole tunneling leakage current (I_(ss)) through the surface states at the n-Si-SiO_2 boundary, the greater the charge accumulated in the quasi-equilibrium hole layer and therefore the higher the voltage across the insulator.