Effect of annealing treatments on photoluminescence and charge storage mechanism in silicon-rich SiN(x):H films

In this study, a wide range of a-SiN(x):H films with an excess of silicon (20 to 50%) were prepared with an electron-cyclotron resonance plasma-enhanced chemical vapor deposition system under the flows of NH(3 )and SiH(4). The silicon-rich a-SiN(x):H films (SRSN) were sandwiched between a bottom thermal SiO(2 )and a top Si(3)N(4 )layer, and subsequently annealed within the temperature range of 500-1100°C in N(2 )to study the effect of annealing temperature on light-emitting and charge storage properties. A strong visible photoluminescence (PL) at room temperature has been observed for the as-deposited SRSN films as well as for films annealed up to 1100°C. The possible origins of the PL are briefly discussed. The authors have succeeded in the formation of amorphous Si quantum dots with an average size of about 3 to 3.6 nm by varying excess amount of Si and annealing temperature. Electrical properties have been investigated on Al/Si(3)N(4)/SRSN/SiO(2)/Si structures by capacitance-voltage and conductance-voltage analysis techniques. A significant memory window of 4.45 V was obtained at a low operating voltage of ± 8 V for the sample containing 25% excess silicon and annealed at 1000°C, indicating its utility in low-power memory devices.