Statement 1: By increasing the rate of recombination and removal of minority carrier, reverse recovery period can be reduced.
Explanation:
- Reverse recovery refers to the time it takes for a diode to switch from the conducting state to the non-conducting state when the voltage polarity across the diode is reversed.
- During the reverse recovery period, the minority carriers (electrons in P-type material and holes in N-type material) that were injected into the diode during the forward conduction have to be removed before the diode can fully block the reverse voltage.
- Increasing the rate of recombination and removal of minority carriers can reduce the reverse recovery period.
- This can be achieved by using techniques such as adding a high reverse voltage across the diode during the reverse recovery period or using a fast recovery diode that has optimized design and material properties to enhance carrier recombination and removal.
- Therefore, statement 1 is correct.

Statement 2: In fast recovery diode, rate of recombination is decreased.
Explanation:
- The rate of recombination in a fast recovery diode is actually increased, not decreased.
- Fast recovery diodes are designed to have a low reverse recovery time by reducing the amount of minority carrier charge stored in the diode during forward conduction.
- This is achieved by optimizing the diode structure and doping profiles to enhance the rate of recombination of minority carriers.
- By increasing the rate of recombination, the stored charge in the diode is quickly depleted during the reverse recovery period, reducing the reverse recovery time.
- Therefore, statement 2 is incorrect.

Statement 3: MOSFET and transistors are used in high power applications.
Explanation:
- MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) and transistors are commonly used in various electronic applications, including high power applications.
- MOSFETs are particularly suitable for high power applications due to their ability to handle high voltage and current levels with low power dissipation.
- They are commonly used in power amplifiers, power converters, motor control circuits, and other high power electronic systems.
- Transistors, such as bipolar junction transistors (BJTs) and insulated gate bipolar transistors (IGBTs), are also used in high power applications.
- BJTs are commonly used in high power amplifiers, switching circuits, and voltage regulators.
- IGBTs combine the advantages of both MOSFETs and BJTs, making them suitable for high power applications that require high voltage and current handling capabilities.
- Therefore, statement 3 is correct.

Statement 4: IGBT is having all the good properties of a transistor and MOSFET.
Explanation:
- IGBTs (Insulated Gate Bipolar Transistors) are a type of transistor that combines the characteristics of both MOSFETs and BJTs.
- They have the high input impedance and voltage control characteristics of MOSFETs, along with the high current and gain characteristics of BJTs.
- IGBTs are capable of handling high voltage and current levels, making them suitable for high power applications.
- They have lower on-state losses compared to BJTs, making them more efficient in high power applications.
- Therefore, statement 4 is correct