Nonvolatile memories by using charge traps in silicon-rich oxides

The nonvolatile memory characteristics of silicon-rich oxide (SRO, SiO x ) grown at room temperature for charge-trapping layer are first reported and shown to exhibit a strong dependence on oxygen content (x). The memory window that is estimated by capacitance-voltage curves monotonically decreases with increasing x from 1.0 to 1.8, possibly resulting from the x-dependent variation in the Si suboxide states responsible for the charge traps, as evidenced by x-ray photoelectron spectroscopy. The density of the charge traps is estimated to be ( 3.9 - 8.8 ) × 10 12 cm − 2 for x = 1.0 - 1.4 . The charge-loss rate sharply decreases at x = 1.2 , but by further increase in x above 1.2, it gradually increases, which can be explained by the lowered SRO / SiO 2 barrier due to the increased optical band gap of SRO at larger x