The paper first analyzes the effect of backlight unit for liquid crystal displays on the respect of image quality and power consumption. A spatially and temporally addressable backlight is required in the future liquid crystal displays which have lower power consumption and higher image quality. Compared to the currently used light emitting diode backlight, the simulation results indicate that a rectangular-shaped backlight has better performances on the respect of reducing power consumption and improving image quality. A backlight cell based on the field emission is manufactured and studied. It uses a mixture of multi-wall carbon nanotubes and tetrapod-like zinc oxide nanostructures as the cathode and applies spin-coating process for fabrication. The experiment shows that such field emission backlight unit has a low turn-on field which enables a high backlight luminance at acceptable driving voltage. Besides, this mixture cathode helps to improve the uniformity of field emission in both spatial and temporal domain which is important for the application of backlight unit.