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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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1
Question
What are the three semiconductor materials mentioned for learning outcomes?
Answer
Si, Ge, GaAs
2
Question
What is the Bohr model as described in the module?
Answer
Planetary atomic structure with nucleus and orbiting electrons
3
Question
What are valence electrons and where are they located?
Answer
Electrons in the outermost shell (valence shell)
4
Question
What happens to valence electrons when energy is absorbed?
Answer
They can break free from the atom (ionization)
5
Question
How is ionization defined in this module?
Answer
Loss of a valence electron from an atom
6
Question
What is a positive ion?
Answer
An atom that has lost one or more electrons in ionization
7
Question
What is a negative ion?
Answer
An atom that has gained one or more electrons
8
Question
What is the significance of valence electrons in conduction?
Answer
They contribute to chemical bonding and electrical properties; free electrons enable conduction
9
Question
How are insulators characterized in terms of valence electrons?
Answer
Tightly bound valence electrons; very few free electrons; high resistivity
10
Question
Name three metals commonly described as good conductors?
Answer
Copper, silver, gold (Cu, Ag, Au)
11
Question
What defines a semiconductor in conductivity?
Answer
Between a conductor and an insulator in conductivity
12
Question
What is the atomic number?
Answer
Number of protons in the nucleus (also equals electrons in neutral atom)
13
Question
What happens to a neutral atom’s charges?
Answer
Positive charges (protons) balance negative charges (electrons) → zero net charge
14
Question
What is meant by the term ‘valence shell’?
Answer
Outermost electron shell of an atom
15
Question
What is the relationship between atomic number and electrons in neutral atoms?
Answer
Equal number of protons and electrons
16
Question
What is an intrinsic semiconductor?
Answer
Pure semiconductor not doped with impurities; not a good conductor or insulator
17
Question
What is the basic idea behind conduction in semiconductors?
Answer
Movement of electrons (and holes) within bands due to energy states
18
Question
What is meant by the conduction band and valence band?
Answer
Conduction band: higher energy band; Valence band: lower energy band occupied by electrons
19
Question
What kind of materials are described as having four valence electrons?
Answer
Tetravalent elements (e.g., Si, Ge)
20
Question
What is ionization energy?
Answer
Energy required to remove a valence electron from an atom
21
Question
How is a free electron created in the context of ionization?
Answer
Valence electron gains enough energy to escape outer shell
22
Question
What happens when a free electron collides with an atom in a neutral state?
Answer
Can be captured, forming a negative ion
23
Question
Give an example of a dopant effect in semiconductors.
Answer
Introduction of donor/acceptor atoms to create n-type or p-type material
24
Question
What term describes a material whose conduction is due to electrons in the conduction band and holes in the valence band?
Answer
Semiconductor conduction via electron and hole theory
25
Question
Which elements are listed as good conductors due to loosely bound valence electrons?
Answer
Cu, Ag, Au, Al (copper, silver, gold, aluminum)
26
Question
What is meant by a covalent bond in semiconductor materials?
Answer
Shared electron pairs between atoms that form a lattice structure
27
Question
What is the focus of Section 1.5.3 in the module?
Answer
Semiconductors and intrinsic conduction properties
28
Question
What does doped mean in semiconductor context?
Answer
Introducing impurities to alter electrical properties (n-type or p-type)
29
Question
What is the primary role of the valence electrons in conduction according to the module?
Answer
Provide free carriers for current (electrons) and holes as vacancies
30
Question
What is the general place of atoms in the periodic table according to atomic number?
Answer
Ordered by increasing atomic number