Temperature dependence of the electrical characteristics of Ag/In_0.53Ga_0.47As diodes formed at low temperature

Schottky contacts on n-In_0.53Ga_0.47As have been made by metal deposition on substrates cooled to a temperature of 77 K. The current-voltage and capacitance-voltage characteristics showed that the Schottky diodes formed at low temperature had a much improved barrier height compared to those formed at room temperature. The Schottky barrier height, φ_B, was found to be increased from ∼0.2 to 0.60 eV with Ag metal. For the low temperature diode, the saturation current density, J₀, was about 4 orders smaller than for the room temperature diode. A transport mechanism dominated by thermionic emission over the barrier for the LT diode was found from current-voltage-temperature measurement. Thermionic field emission is seen for the higher doped substrate with reverse bias. Deep level transient spectroscopy studies of n-InGaAs low temperature diodes exhibited a bulk electron trap at E_c - 0.23 eV. The low temperature process appears to reduce metal induced surface damage and may form an MIS-like structure at the interface.