Abstract: A capacitor is provided for high temperature systems. The capacitor includes: a substrate formed from silicon carbide material; a dielectric stack layer, including a first layer deposited on the substrate and a second layer deposited on the first layer; a Schottky contact layer deposited on the second layer; and an Ohmic contact layer deposited on the substrate. The first layer is formed with aluminum nitride (AlN) epitaxially, and the second layer is formed with aluminum oxide (Al2O3). AlN and Al2O3 are ultrawide band gap materials, and as a result, they can be use as the dielectric in the capacitor, allowing the capacitance changes to be less than 10% between ?250° C. and 600° C., which is very effective for the high temperature systems.