TEMPERATURE-DEPENDENCE OF THE ELECTRICAL CHARACTERISTICS OF AG/IN0.53GA0.47 AS DIODES FORMED AT LOW-TEMPERATURE

Schottky contacts on n-In0.53Ga0.47As 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, phi(B), was found to be increased from approximately 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.