Diode Types

Breaking Down the Basics

Diodes are an electronic component that often acts as a semiconductor. A semiconductor is a particular material that conducts electricity to a varying degree. Semiconductors will often employ a process known as "doping" where a small amount of an impurity is mixed into the silicon crystal, allowing the degree of conductivity to change in order to fulfill a specific requirement. In a circuit, a diode will direct the flow of electricity in one direction while preventing electrical flow in the opposite direction. In essence, one can say that diodes act as sort of a traffic controller for a circuit. For example, a common application of a diode is in a device with user-replaceable batteries. If the battery is installed backwards, the diode will block the current from leaving the battery.

Light Emitting Diodes (LED's)

LED from IDECLight Emitting Diode, or LEDWEG Electric style LEDLSTD-M4R LED from IDECDiodes are useful in a variety of applications. One type of diode that you may interact with every day is a Light Emitting Diode, or LED. LED's have a number of advantages over traditional light bulbs. They are compact, durable, and last much longer than a traditional light bulb with a filament. Arguably the biggest advantage of LED's however, is that they are very efficient. They produce very little heat, meaning that much less electricity is wasted. LEDs generally boast a relatively simple construction, allowing for wide versatility across a variety of applications, from something as simple as handheld flashlights and digital clocks all the way to HD television sets.

Other Types of Diodes

There are a variety of products that also fall under the category of "Diode". Some of these components include:

• Photodiodes - Photodiodes are another common type of diode. A photodiode is typically a PN junction or PIN structure, and will typically be used to convert light into current or voltage. Solar cells are often just a large photodiode. Photodiodes are even commonly used in some consumer devices such as CD Players, smoke detectors, and the receivers for remote controls.
• Zener Diodes - Another commonly-used type of diode is the Zener Diode. Like a traditional semiconductor diode, a Zener diode directs the flow of a current forward in one direction, but a feature unique to a Zener diode is that when the voltage exceeds a certain value, (often referred to as the "breakdown voltage"), the Zener diode will allow the current to flow in the opposite direction. Zener diodes and avalanche diodes have very similar properties. In silicon diodes up to 5.6 volts, the Zener effect will be the predominant effect and will show a negative temperature coefficient, while above 5.6 volts the avalanche effect becomes the predominant effect, and will instead exhibit a negative temperature coefficient. Because of this property, you can often find this particular type of diode in a surge protector.
• Schottky Diodes - Schottky diodes (also known as "hot carrier diodes") are diodes with a low forward voltage drop with a very fast switching action. Schottky diodes feature a much lower voltage drop compared to a conventional silicone diode (typically 0.15-0.45 in a Schottky diode vs. 0.6-1.7 in a traditional silicon diode). Better system efficiency can be achieved due to the reduced voltage drop and increased switching speed. The low voltage drop in these diodes means that less energy is wasted as heat, resulting in them being the most efficient choice for efficiency-sensitive applications. Schottky diodes feature a reverse recovery time. When switching from a conducting to a non-conducting state, a traditional diode can take several hundred nanoseconds to recover, while Schottky diodes do not have a recovery time at all. Schottky diodes do have some limitations, however. They have a somewhat low reverse voltage rating, and a relatively high reverse leakage current.
• Avalanche Diodes - Avalanche Diodes are diodes designed to go through avalanche breakdown at a specific reverse bias voltage. An avalanche breakdown is similar to the Zener breakdown found in Zener diodes (in fact, both diodes experience both types of breakdowns), but avalanche diodes are optimized for the avalanche effect due to their small but significant voltage drop under breakdown conditions. Avalanche diodes also have a small positive temperature coefficient of voltage, while Zener diodes will have a negative temperature coefficient. Avalanche diodes are often used to protect electronic circuits against potentially-damaging high voltages. They can also be used to generate RF (radio frequency) noise, allowing for use in radio equipment, white noise generators, and hardware number generators.