InSb gate-controlled diodes were fabricated to study breakdown behavior and surface effects. I- Vcharacteristics were measured as a function of gate voltage and temperature. The results indicated that a field-induced junction was formed as the negative bias exceeded —4 V. The field induced junction was found to have a breakdown voltage smaller than that of the metallurgical junction. Saturation of the breakdown current in the field-induced junction was also observed, which could be explained by the conducting channel effect similar to that in the metal oxide semiconductor field effect transistor (MOSFET). The reverse current was also measured as a function of temperature to study the leakage mechanism. The strong exponential temperature dependence suggested that the reverse current was dominated by the G- R mechanism.