6.3 Schottky Diodes
* Barrier potential created at anode silicon-metal interface eliminates charge storage problems
* Metal layer deposited on thin epitaxial layer of N types silicon
* There are no minority carriers so recombination time does not exist and rectification only depends on majority carriers
* Recovery time only influenced by capacitance of silicon-metal interface
* Have relatively low forward voltage drops dependant on doping levels and thus barrier potential (0.2 - 0.9V)
* Leakage currents are higher ( >100mA)
* Low current ratings (1 - 300A)
* Low voltage ratings ( <100V)
6.4 Power Zener Diodes
* Zener diode more highly doped and designed to operate in breakdown region
* Breakdown above ~5V is avalanche rather than zener (limit current and no problem)
* Zener voltage levels over a wide range ( < 300V)
* Continuous power rating over moderate range (250mW - 75W)
* Can be used in transient suppression as a clamp and absorb up to 50kW for limited times