Field-induced functions of porous Si as a confined system

Electroluminescent porous Si (PS) diodes exhibit various useful functions u nder a high-electric held. The experimental PS diodes are composed of thin semitransparent metal films, PS layers (about 500 nm thick in minimum), p- or n-type Si substrates and ohmic back contacts. Definite nonlinear electri cal behavior (negative resistance and nonvolatile bistable memory effects) and cold electron emission phenomena appear in these PS diodes associated w ith the EL emission. Both the negative resistance and memory effects are re lated to the charging of Si nanocrystallites by held-induced carrier inject ion. The electron emission observed in the PS diodes formed on n + -Si subs trates is caused by hot electrons tunnelling through the top contact. By an appropriate structural control of PS, the effective drift length under a h igh-field conduction is significantly increased, and then electrons are emi tted ballistically. These functions reflect the activity of PS as a nanocry stalline confined system. (C) 1999 Published by Elsevier Science B.V. All r ights reserved.