A Schottky Barrier Diode (SBD), also known as a Schottky diode or hot-carrier diode, is a semiconductor device that forms a metal-semiconductor junction. Unlike conventional p-n junction diodes, the Schottky diode uses a metal (usually platinum, aluminum, or gold) as the anode and a semiconductor material (such as silicon) as the cathode. The metal-semiconductor interface creates a barrier that controls the flow of charge carriers through the diode.
When a forward bias voltage is applied to the Schottky diode, meaning the anode (metal side) is at a higher potential than the cathode (semiconductor side), the barrier at the metal-semiconductor junction reduces, allowing electrons to move from the semiconductor to the metal. On the metal side, a majority of charge carriers are electrons. On the semiconductor side, the charge carriers are both electrons and holes (the absence of electrons).
The absence of a p-n junction in Schottky diodes makes them fast-switching devices, as they don't have any stored charge in the depletion region to slow down the switching process. This property makes them suitable for high-frequency applications.
Low forward voltage drop: Schottky diodes have a lower forward voltage drop (typically around 0.2 to 0.3 volts) compared to conventional p-n junction diodes (around 0.6 to 0.7 volts). This characteristic reduces power losses and results in faster switching speeds.
Fast switching speed: Due to the absence of a depletion region in the junction, the charge carriers can move quickly across the metal-semiconductor interface, making Schottky diodes ideal for high-frequency and high-speed applications.
Low reverse recovery time: Schottky diodes have minimal reverse recovery time because there are no minority carriers to be removed from the depletion region when switching from forward bias to reverse bias. This property reduces switching losses and allows them to handle high-frequency signals efficiently.
Temperature sensitivity: Schottky diodes have a higher temperature coefficient of voltage than regular diodes. This means their forward voltage drop decreases with increasing temperature, which can be advantageous in certain applications.
Leakage current: Schottky diodes have higher reverse leakage currents compared to conventional p-n junction diodes. Therefore, they may not be as suitable for applications that require very low reverse currents.
Schottky diodes are commonly used in various applications, including rectification in power supplies, voltage clamping, and high-frequency circuits such as mixers and detectors. Their unique characteristics make them well-suited for specific tasks where fast switching and low forward voltage drop are essential. However, it's important to consider their higher reverse leakage current and select appropriate cooling mechanisms for high-power applications to prevent overheating.