A semiconductor device and method of fabricating the same are provided. In one embodiment, the semiconductor device includes a memory transistor with an oxide-nitride-nitride-oxide (ONNO) stack disposed above a channel region. The ONNO stack comprises a tunnel dielectric layer disposed above the channel region, a multi-layer charge-trapping region disposed above the tunnel dielectric layer, and a blocking dielectric layer disposed above the multi-layer charge-trapping region. The multi-layer charge-trapping region includes a substantially trap-free layer comprising an oxygen-rich nitride and a trap-dense layer disposed above the trap-free layer. The semiconductor device further includes a strain inducing structure including a strain inducing layer disposed proximal to the ONNO stack to increase charge retention of the multi-layer charge-trapping region. Other embodiments are also disclosed.