Electrical and optical characterization of back-to-back Schottky (Al,Ga)As/NiAl/(Al,Ga)As molecular beam epitaxially grown double-heterostructure diodes

Current-voltage, capacitance-voltage, and internal photoemission measurements of back-to-back Schottky diodes of buried metal (Al,Ga)As/NiAl/(Al,Ga)As double heterostructures grown by molecular beam epitaxy are reported. By using a selective etch process to access the buried layers and fabricate three-terminal devices, independent measurements of the barrier height on both sides of the buried metal double heterostructure were performed. Schottky diode behavior was observed for both upper and lower diodes and the barrier height was measured to be 1.1 eV for both diodes using internal photoemission. Electrical measurements showed a lower effective barrier height for the upper metal-semiconductor interface as compared to the lower interface in agreement with the different defect densities in these heterostructures.