the Schottky diode
/ SHOT-kee /
A Schottky diode is a diode made by pressing a metal against a semiconductor instead of joining P-type and N-type silicon. That different junction gives it two prized properties: a low forward drop (about 0.2 to 0.4 V instead of 0.7 V) and very fast switching. It is the 'quick, low-loss' diode in the toolbox.
Why the low drop and speed? The metal-semiconductor junction conducts using majority carriers only, so there is no slow 'stored charge' to sweep out when it switches off — it turns off almost instantly, unlike a normal diode that lingers for a moment. And the barrier itself is lower, so it starts conducting at a smaller voltage. Lower drop means less wasted heat in a rectifier; faster switching means it works cleanly at high frequency.
That makes Schottkys the default in switching power supplies, high-frequency rectifiers, flyback catch diodes, and anywhere the 0.7 V of a silicon diode is too costly. The trade-offs are honest: Schottkys have higher reverse leakage (worse when hot), a lower reverse breakdown voltage, and the leakage can thermally run away — so they are not a free upgrade, just the right tool for low-voltage, high-speed work.
Swap a silicon rectifier (0.7 V) for a Schottky (0.4 V) in a 3 A, 5 V supply and you save (0.7 - 0.4) times 3 = 0.9 W of heat per diode — and the lower drop means more usable voltage reaches the load.
Schottky: about 0.3 V less drop and far faster, at the cost of more reverse leakage.
A Schottky is not a drop-in for every diode: its lower reverse breakdown and higher leakage make it a poor choice for high-voltage blocking, and the leakage worsening with heat can run away. Match it to low-voltage, high-frequency jobs.