High barrier height Schottky diodes on n-InP by low temperature deposition

The formation of ultra-high barrier height (φ_B = 0.96 eV) Schottky contacts to n-InP, without an intentionally grown interfacial oxide, using metal deposition on a substrate cooled to as low as 77 K is discussed. Values of φ_B = 0.46-0.52 eV for diodes deposited at room temperature (RT = 300 K) agree and give an ideality factor near unity. For diodes deposited at a low temperature (LT) of 77 K, the leakage current density (J₀) is reduced by more than 6-7 orders of magnitude with respect to the RT diodes. The φ_B for the LT diodes is increased from 0.48 to 0.96 eV for Pd metal and from 0.51 to 0.85 eV for Au metal, respectively. The conduction mechanisms for the LT and RT diodes are found to be controlled by thermionic-field emission (TFE) and thermionic emission (TE), respectively. It is shown that an alteration of the metal-induced interface states, inhibition of surface segregation of the released In and P atoms, and very uniform metal coverage may be responsible for the distinct differences between the RT and LT diodes.