Characterization of n-n Ge/SiC heterojunction diodes

In this paper we investigate the physical and electrical properties of germanium deposited on 4H silicon carbide substrates by molecular beam epitaxy. Layers of highly doped and intrinsic germanium were deposited at 300 and 500 °C and compared. Current-voltage measurements reveal low turn-on voltages. The intrinsic samples display ideality factors of 1.1 and a reverse leakage current of 9×10−9 A/cm2, suggesting a high quality electrical interface. X-ray diffraction analysis reveals the polycrystalline nature of the high-temperature depositions, whereas the low-temperature depositions are amorphous. Atomic force microscopy shows that the low-temperature layers have a rms roughness of 3 nm.