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Semiconductor Basics Si Ge GaAs
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Semiconductor Basics Si Ge GaAs
Semiconductor Basics Si Ge GaAs
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What are the three semiconductor materials mentioned for learning outcomes?
Si, Ge, GaAs
What is the Bohr model as described in the module?
Planetary atomic structure with nucleus and orbiting electrons
What are valence electrons and where are they located?
Electrons in the outermost shell (valence shell)
What happens to valence electrons when energy is absorbed?
They can break free from the atom (ionization)
How is ionization defined in this module?
Loss of a valence electron from an atom
What is a positive ion?
An atom that has lost one or more electrons in ionization
What is a negative ion?
An atom that has gained one or more electrons
What is the significance of valence electrons in conduction?
They contribute to chemical bonding and electrical properties; free electrons enable conduction
How are insulators characterized in terms of valence electrons?
Tightly bound valence electrons; very few free electrons; high resistivity
Name three metals commonly described as good conductors?
Copper, silver, gold (Cu, Ag, Au)
What defines a semiconductor in conductivity?
Between a conductor and an insulator in conductivity
What is the atomic number?
Number of protons in the nucleus (also equals electrons in neutral atom)
What happens to a neutral atom’s charges?
Positive charges (protons) balance negative charges (electrons) → zero net charge
What is meant by the term ‘valence shell’?
Outermost electron shell of an atom
What is the relationship between atomic number and electrons in neutral atoms?
Equal number of protons and electrons
What is an intrinsic semiconductor?
Pure semiconductor not doped with impurities; not a good conductor or insulator
What is the basic idea behind conduction in semiconductors?
Movement of electrons (and holes) within bands due to energy states
What is meant by the conduction band and valence band?
Conduction band: higher energy band; Valence band: lower energy band occupied by electrons
What kind of materials are described as having four valence electrons?
Tetravalent elements (e.g., Si, Ge)
What is ionization energy?
Energy required to remove a valence electron from an atom
How is a free electron created in the context of ionization?
Valence electron gains enough energy to escape outer shell
What happens when a free electron collides with an atom in a neutral state?
Can be captured, forming a negative ion
Give an example of a dopant effect in semiconductors.
Introduction of donor/acceptor atoms to create n-type or p-type material
What term describes a material whose conduction is due to electrons in the conduction band and holes in the valence band?
Semiconductor conduction via electron and hole theory
Which elements are listed as good conductors due to loosely bound valence electrons?
Cu, Ag, Au, Al (copper, silver, gold, aluminum)
What is meant by a covalent bond in semiconductor materials?
Shared electron pairs between atoms that form a lattice structure
What is the focus of Section 1.5.3 in the module?
Semiconductors and intrinsic conduction properties
What does doped mean in semiconductor context?
Introducing impurities to alter electrical properties (n-type or p-type)
What is the primary role of the valence electrons in conduction according to the module?
Provide free carriers for current (electrons) and holes as vacancies
What is the general place of atoms in the periodic table according to atomic number?
Ordered by increasing atomic number
