Direct-current and alternating-current electroluminescence of MOS capacitors with Si-implanted SiO2

The direct-current and alternating-current electroluminescence (d.c.- and a.c.-EL) characteristics of n(+)-polysilicon MOS capacitors with 50 nm Si-implanted SiO2 have been measured to discuss EL stability and frequency response. While the d.c.-EL intensity increases with time I at small constant current density (J(G)) and decreases for large J(G), it decreases with I monotonously under constant gate voltage (V-G) condition. The time dependence of the d.c.-EL intensity has been modeled with two kinds of states in the oxide layer. The a.c.-EL intensity for samples with various Si implantation conditions increases with frequency except for samples without Si implantation or with low energy implantation. The above implies that Si implantation produces slow states near the oxide-Si interface. A.c.-operation remarkably improved the EL intensity and time dependence. It may be attributed to an increase of effective current due to charge stored under alternating bias conditions. (C) 1998 Elsevier Science Ltd. All rights reserved.