The structural, optical, and electrical characteristics of An<SUB>0.8</SUB>Mg<SUB>0.2</SUB>O/ZnO/Zn<SUB>0.8</SUB>Mg<SUB>0.2</SUB>O quantum well heterostructures, are reported. The structures consist of a ZnO quantum well, with thickness of 6 nm, 8 nm, or 50 nm, placed between two Zn<SUB>0.8</SUB>Mg<SUB>0.2</SUB>O barriers, with a thickness of 7nm. The epitaxial layers are grown by pulsed laser deposition (PLD) on c-cut sapphire substrates. Resonant tunneling action in the 6 nm and 8 nm width single quantum well has been observed. Negative differential resistance (NDR) peaks were evident at room temperature and at 200 K in this system for the first time. X-ray diffraction spectra showed high crystal quality, and pulsed photoluminescence measurements showed high quality hetero- interfaces with a FWHM of 5.6 meV at 77K. The photoluminescence (PL) transitions in the quantum wells occurred at wavelengths of 345.55 nm and 348.22nm for the 6 nm and 8 nm well width respectively. The current-voltage characteristics of the structures showed the negative differential resistance peaks at RT and 200 K, making this type of wide band-gap semiconductor material system a very promising system for applications both in electron transport and in UV detector devices.