Summary, Concept Map

Semiconductor Electronics | Physics

SUMMARY

• Energy bands in solids are used to classify them into metals, insulators, and semiconductors

• In a N-type semiconductor, electrons are the majority charge carriers and holes are the minority carriers

• In P-type semiconductor, holes are the majority charge carriers and electrons are the minority charge carriers

• A depletion region is formed in an unbiased PN junction. It is devoid of mobile charge carriers. Instead, it has immobile ions

• When a PN junction diode is forward biased, the depletion region decreases and the diode conducts once after the barrier potential is crossed. It acts like a closed switch.

• A PN junction diode in reverse biased condition functions as a open switch as it does not conduct. The depletion region increases.

• A forward biased PN junction diode functions as a rectifier. Rectification is the process of converting an AC current into DC current

• The half wave rectifier rectifies one half of the input signal and produces a pulsating output.

• Full wave rectifier rectifies both halves of the input signal.

• The efficiency of the full wave rectifier is two times the efficiency of the half wave rectifier

• The two mechanisms that is responsible for breakdown under increasing reverse voltage: Zener and Avalanche breakdown

• Zener breakdown happens in a heavily doped PN junction diode when a strong electric field is applied.

• Avalanche breakdown occurs in lightly doped junctions which have wide depletion layers. It is due to the breaking of covalent bonds by the thermally generated minority charge carriers.

• Zener diode is a heavily doped PN junction diode works in the reverse biased direction

• Light emitting diode is a forward biased semiconductor device that emits emits visible or invisible light when energized. The recombination of minority charge carriers with the majority charge carriers in the respective regions release energy in the form of Photons.

• A PN junction diode made of photosensitive material converts an optical signal into electric signal is called a photodiode.

• When a photon of sufficient energy strikes the diode, it creates an electron-hole pair. These electrons and holes are swept across the p-n junction by the electric field created by reverse voltage before recombination takes place and in turn generates photo current.

• A solar cell is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect.

• A bipolar junction transistor is a semiconductor device is of two types: NPN and PNP.

• BJT has three regions: emitter, base, and collector

• To operate the transistor in the active region, emitter base must be forward biased and collector base must be reverse biased.

• A BJT can be operated in three different configurations: Common base, common emitter, common collector.

• The forward current gain in common base configuration α gives the ratio of the collector current to emitter current.

• The forward current gain in common emitter configuration β gives the ratio of the collector current to the base current

• The BJT connected in common emitter configuration functions as a switch

• The BJT connected in common emitter configuration can be used as an amplifier. There exists a phase reversal of 1800 between the input signal and the amplified output signal.

• A transistor amplifier combined with a tank circuit and positive feedback acts as an oscillator

• The logic gates are logical circuits provides output only for a combination of inputs.

• The basic logic gates are AND, OR, and NOT gates.

• Boolean algebra is used to simplify complicated expressions and hence to simplify the logic circuit.

• De Morgan’s First theorem states that the complement of the sum of two inputs is equal to the product of its complements.

• The second theorem states that the complement of the product of two inputs is equal to the sum of its complements.

CONCEPT MAP