Semiconductor Diode – Class 12 | Chapter – 14 | Physics Short Notes Series PDF for NEET & JEE

Semiconductor Diode: A semiconductor diode is a device that consists of a p-n junction, which allows current to flow in one direction but blocks it in the opposite direction. When a positive voltage is applied to the p-type material and a negative voltage to the n-type material, the diode is forward-biased, and current can flow through the junction. When the polarity is reversed, the diode is reverse-biased, and current is blocked.

Types of Semiconductor Diode

There are several types of semiconductor diodes. Here are some of the most common ones:

  • Rectifier diode: This is the most common type of diode, used to convert alternating current (AC) to direct current (DC) in power supplies.
  • Zener diode: This diode is designed to operate in the reverse breakdown region, and is used as a voltage regulator.
  • Schottky diode: This diode has a low forward voltage drop and fast switching times, and is commonly used in high-frequency applications.
  • Light-emitting diode (LED): This diode emits light when forward biased, and is commonly used in lighting applications.
  • Photodiode: This diode is sensitive to light, and is commonly used in light sensing and detection applications.
  • Varactor diode: This diode has a variable capacitance that changes with the applied voltage, and is commonly used in voltage-controlled oscillators and frequency synthesizers.
  • Tunnel diode: This diode has a negative resistance characteristic, and is commonly used in high-speed and low-noise applications.
  • PIN diode: This diode has a wide intrinsic (undoped) region between the p-type and n-type layers, and is commonly used in RF and microwave applications as a variable resistor.

Applications of Semiconductor Diode

Semiconductor diodes have a wide range of applications in electronic circuits. Some of the most common applications include:

  • Rectification: Diodes can be used to convert AC voltage to DC voltage by blocking the negative half of the AC cycle and allowing only the positive half to pass.
  • Voltage regulation: By combining diodes and resistors, it is possible to create a simple voltage regulator that can provide a constant output voltage despite variations in the input voltage.
  • Signal detection: Diodes can be used to detect signals in radio and TV circuits, where they are used to extract the audio and video signals from the carrier wave.
  • Clamping: Diodes can be used to clamp the voltage of a signal to a certain level. For example, a diode can be used to prevent the voltage of a signal from exceeding a certain value.
  • Protection: Diodes can be used to protect sensitive electronic components from voltage spikes and other transient events. For example, diodes can be used in reverse-biased configuration to protect against voltage spikes in a circuit.
  • Lighting: LEDs are a type of diode that emits light when forward-biased. They are widely used in lighting applications, such as indicator lights, traffic lights, and backlighting for displays.

Characteristics of Semiconductor Diode

Semiconductor diodes have several important characteristics that make them useful in a wide variety of electronic applications. Here are some of the key characteristics of semiconductor diodes:

  • Current-voltage (IV) characteristic: The current-voltage characteristic of a diode is nonlinear and can be described by an exponential equation. In the forward direction, the diode has a low resistance and allows current to flow easily. In the reverse direction, the diode has a high resistance and does not allow current to flow.
  • Forward voltage drop: When a diode is forward biased, it has a forward voltage drop that is typically around 0.7 volts for a silicon diode and 0.3 volts for a germanium diode. This voltage drop is dependent on the material and doping used in the diode.
  • Reverse breakdown voltage: If a diode is reverse biased and the voltage is increased, eventually the reverse breakdown voltage will be reached and the diode will conduct in the reverse direction. The reverse breakdown voltage is also dependent on the material and doping used in the diode.
  • Junction capacitance: The depletion region of a diode acts like a capacitor, with a junction capacitance that varies with the applied voltage. This capacitance can have an effect on the performance of high-frequency circuits.
  • Thermal characteristics: Diodes have a maximum junction temperature and a maximum power dissipation that should not be exceeded in order to avoid damage to the device.
  • Response time: Diodes have a response time, which is the time it takes for the diode to switch from conducting to non-conducting (or vice versa) when the bias voltage is changed. This response time is dependent on the material and doping used in the diode.

Biology Quiz & Notes Physics Quiz & Notes Chemistry Quiz & Notes

Follow on Facebook

By Team Learning Mantras