A Schottky diode is like a regular diode, except is has some advantages and disadvantages. This is the symbol for it:
...
One advantage is that the Schoottky diode has a smaller forward voltage (which minimizes the power wasted), which is the voltage needed to let current through. Another advantage is that it also wastes less power than a regular diode. But the biggest advantage is that it has fast switching speeds, so it can be used with high-frequency circuits, which is good for rectification.
The downside to using Schottky diodes is that it has a greater leakage current than a regular silicon diode.
The following graph shows everything:
...
Notice how both the Schottky and PN diode are almost the same. Examining the first quadrant, we can see that the blue line raises faster, thereby showing how it has a smaller fwd voltage (it lets current though at lower voltages). In the third quadrant, notice how the blue line shows more current than the red line, when in the reverse direction. This is the disadvantage of having a greater leakage current. Since no diode is perfect, a Schottky diode lets more current in the reverse mode than a regular diode.
Schotty diodeshave many useful applications from rectification, signal conditioning and switching, through to TTL and CMOS logic gates due mainly to their low power and fast switching speeds.