Non-volatile memory devices and arrays are described that utilize dual gate (or back-side gate) non-volatile memory cells with band engineered gate-stacks that are placed above or below the channel region in front-side or back-side charge trapping gate-stack configurations in NAND memory array architectures. The band-gap engineered gate-stacks with asymmetric or direct tunnel barriers of the floating node memory cells of embodiments of the present invention allow for low voltage tunneling programming and efficient erase with electrons and holes, while maintaining high charge blocking barriersand deep carrier trapping sites for good charge retention. The memory cell architecture also allows for improved high density memory devices or arrays with the utilization of reduced feature word lines and vertical select gates.