Silicon diodes are diodes in which the P and N materials are made of silicon. Silicon Diode have a a forward bias voltage of 0.7 volts. That is, the diode conducts when the voltage across the it in the forward bias is 0.7 volts or greater.
They are the most widely used diodes in the industry. Other diodes such as Germanium diodes are used at voltages below 0.7 volts.
The diode can withstand a voltage of 50V or more in the reverse direction. This is known as the peak inverse Voltage.