Techniques and circuitry are disclosed for efficiently implementing programmable memory array circuit architectures, including both non-volatile and volatile memories. The memory circuitry employs an antifuse scheme that includes an array of 1 T bitcells, wherein each bitcell effectively contains one gate or transistor-like device that provides both an antifuse element and a selector device for that bitcell. In particular, the bitcell device has asymmetric trench-based source/drain contacts such that one contact forms a capacitor in conjunction with the spacer and gate metal, and the other contact forms a diode in conjunction with a doped diffusion area and the gate metal. The capacitor serves as the antifuse element of the bitcell, and can be programmed by breaking down the spacer. The diode effectively provides a Schottky junction that serves as a selector device which can eliminate program and read disturbs from bitcells sharing the same bitline/wordline.