U.S. Pat. No. 5,982,015 corresponding to JP-A-11-233795 discloses a lateral diode used as a freewheeling diode (FWD) connected in parallel to a semiconductor switching element such as an insulated gate bipolar transistor (IGBT). The anode of the lateral diode has both ohmic contact and Schottky contact so that the accumulation of holes can be reduced. Accordingly, the reverse recovery charge Qrr is reduced so that the reverse recovery capability can be improved. That is, the Schottky contact reduces the electronic injection. Therefore, even when the hole injection can be reduced without reducing the amount of current. Thus, the reverse recovery charge Qrr is reduced so that the reverse recovery capability can be improved.
As described above, when the anode of the lateral diode has both ohmic contact and Schottky contact, the reverse recovery charge Qrr is reduced so that the reverse recovery capability can be improved. However, the avalanche capability cannot be improved. Therefore, it is likely that the avalanche breakdown occurs during a high speed switching operation.