Semiconductor Fundamentals: Properties, Devices, and Applications
Semiconductor Fundamentals
Introduction to Semiconductors
Semiconductor: A substance that behaves as a conductor or insulator, such as silicon or germanium.
Crystal Structure
The way atoms bind to form a material. In its pure state, atoms are arranged in a repeating pattern.
Key Concepts in Semiconductors
Recombination
The process where a free electron fills a hole in an atom within a semiconductor material doped with impurities.
Bound Electron
An electron that is in orbit around an atom. Ionization energy is required to release it.
Electron Hole
The absence of an electron in the valence band.
Valence Electron
Electrons in the outermost energy levels, responsible for interactions between atoms.
Thermal Generation
The phenomenon where an electron leaves its position to fill a hole, simultaneously creating another hole in its original position, producing energy.
Majority Carrier
Atoms with excess electrons, typically found in N-type (negative) semiconductors doped with pentavalent impurities.
Minority Carrier
Atoms with a deficit of electrons, typically found in P-type (positive) semiconductors doped with trivalent impurities.
Intrinsic Material
Chemically pure semiconductor material.
Extrinsic Material
Semiconductor material that has undergone doping with impurities.
Contact Potential or Potential Barrier
The phenomenon where electrons cross the boundary between P and N-type materials, creating a potential difference.
Depletion Zone or Barrier Region
A non-conductive region within a PN junction, devoid of free charge carriers, acting as a potential barrier.
Polarization of a Pure Semiconductor at Absolute Zero
The semiconductor possesses insufficient energy for electrical conduction.
Polarization of a Pure Semiconductor at Room Temperature
Thermal energy breaks some atomic bonds, freeing electrons and enabling conduction.
Covalent Bond
A bond where electrons are shared between two atoms.
Diodes and Rectification
Anode
P-type (positive) terminal of a diode.
Cathode
N-type (negative) terminal of a diode.
Direct Polarization (Forward Bias)
Applying a positive voltage to the P-type region and a negative voltage to the N-type region of a PN diode, allowing current to flow.
Reverse Bias
Applying a negative voltage to the P-type region and a positive voltage to the N-type region of a PN diode, blocking current flow.
Zener Diode
A silicon diode designed to operate in the reverse breakdown region, often used for voltage regulation and protection.
Rectification
The process of converting alternating current (AC) to direct current (DC).
Half-Wave Rectifier
A circuit that eliminates either the positive or negative half of an AC signal.
Full-Wave Bridge Rectifier
A circuit that converts both halves of an AC signal into pulsating DC.
Full-Wave Rectifier with Center-Tapped Transformer
A circuit that utilizes a transformer with a center tap to achieve full-wave rectification.
Three-Phase Half-Wave Rectifier
A rectifier circuit used with three-phase AC power.
Six-Phase Full-Wave Rectifier
A rectifier circuit that produces a smoother DC output compared to other configurations.
Filters
Filters in Rectifier Circuits
Systems used to reduce variations in pulsating DC voltage.
Capacitor Filter
A circuit using a diode and capacitor to smooth the output voltage.
Action of the Capacitor
The capacitor stores energy during the rising portion of the AC cycle and releases it during the falling portion, reducing voltage fluctuations.
Ripple Voltage
The variation in output voltage after filtering. Lower ripple voltage indicates better filtering.
RC Filter
An improved filter using a resistor and capacitor combination.
LC Filter
A filter combining an inductor and capacitor for further smoothing of the output voltage.
Other Components and Concepts
Diode Bridges
Used for rectifying current and maintaining a stable voltage.
Optoelectronics
Devices that can generate and manipulate light, often involving semiconductors.