Charge-Trapping-Induced Hysteresis Effects in Highly Doped Silicon Metal-Oxide-Semiconductor Structures

It is shown that a simple metal-oxide-semiconductor (MOS) structure with highly doped silicon substrate can exhibit current-voltage hysteresis effects related to sudden rises and drops in the flowing electric current. Experimental current-voltage characteristics of Al-SiO -(n++Si) structures are presented and discussed. Their analysis shows that the ohmic and shallow traps assisted space-charge limited conduction (SCLC) are the dominating transport mechanisms. Sudden rises and drops in the flowing current, leading to the current-voltage hysteresis effects, are attributed to tunneling through deep traps in the oxide. Based on inelastic electron tunneling spectroscopy (IETS), the energy levels of the deep traps and their position in the oxide are evaluated.