Abstract
Schottky barrier enhancement by low temperature (LT = 77K) deposition has successfully achieved. The barrier height φ B of 0.64eV was obtained at LT, comparing the same contact formed at room temperature (RT) with a φ B of 0.30eV. Current transport mechanisms were studied on Schottky contacts formed at LT and RT. Based on theoretic fitting of the current-voltage (I-V) plots at different temperatures, it was found that the recombination current in the depletion region may be responsible for the I-V characteristics deviation from the ideal thermionic emission (EM) model. The recombination current can be caused by deep defect level in InGaAs. This effect became more significant on diodes with lower barrier height, under lower bias, and at low measurement temperature. The generation current, however, has only a small effect on the reverse biased current. A deep defect level located at 0.321eV below the bottom of the conduction band in InGaAs, identified by the deep level transient spectroscopy (DLTS) measurement, can act as the recombination-generation center. The generation lifetime of this center may be much longer than its recombination lifetime, so that it may affect the forward bias I-V characteristics more severely.