Which one is not a trivalent impurity?

Which one is not a trivalent impurity?

Phosphorus is a pentavalent element, which implies it has five valence band elections. Which of the following is not a trivalent impurity atom, according to this debate? A Boron; B Indium; C Gallium; and D Phosphorus Option "D" is the right answer. Phosphorus has five valence electrons in its fifth orbital, which means that it can only form four bonds. Because phosphorus has only three valence electrons left over after bonding with other elements, it is considered a trivalent impurity atom.

Boron, indium, gallium, and arsenic are all tetravalent impurities because they have enough electrons to form only four bonds. They cannot be trivalent because then they would have less than the required number of electrons to be stable.

Tetravalent impurities include beryllium, cadmium, mercury, thallium, and lead. The term "pentavalent impurity" means that it has five valence electrons in its fifth orbital. Elements with these valences include phosphorus, antimony, arsenic, sulfur, selenium, and oxygen. Pentavalent impurities do not include trivalent atoms such as aluminum, calcium, copper, iron, magnesium, neon, sodium, zinc, and yttrium.

The correct answer is option "D".

What are other names for the pentavalent and trivalent atoms?

The atomic structure of pentavalent (phosphorus) and trivalent (boron) atoms is seen in the figure below. Phosphorus is a material made up of atoms with the same amount of protons. Thus, it has the same number of electrons as oxygen - 14. However, because its outermost electron shell is full, it can't be part of an atom with less than 14 electrons. Bismuth has the same number of electrons as phosphorus - 14. But because it has an inner core of electrons, it can join with another bismuth to make a compound.

Trivalent atoms have three valence electrons. They can form two covalent bonds with other elements. Gallium has 29 electrons in its outer shell, so cannot be combined with anything else. Indium has 49 electrons in its outer shell. Technetium has 67 electrons in its outer shell. These elements cannot be combined with other elements because they do not have the proper number of electrons in their outer shells.

Pentavalent atoms have five valence electrons. Chromium has 51 electrons in its outer shell. Manganese has 52 electrons in its outer shell. Iron has 58 electrons in its outer shell. Nickel has 59 electrons in its outer shell. These elements can be combined together to form compounds.

Which of them is a pentavalent impurity in a semiconductor?

Pentavalent impurities are atoms having five valence electrons that are employed in semiconductor doping. For example, arsenic (As), phosphorous (Pi), antimony (Sb), and so on. Pentavalent impurities have the potential to become bond with other elements so they should be kept as low concentration as possible.

Bonded pairs of dopants act as recombination centers for electrons and holes, thereby reducing device performance and lifetime. Therefore, it is important to avoid introducing high concentrations of impurities into semiconductors. Impurities can be introduced during growth or treatment of the material after fabrication. For example, excess As in Si substrates causes p-type defects which can be eliminated by an As anneal.

Ion implantation is used to introduce specific amounts of impurities into semiconductor materials. The maximum allowable concentration of each type of impurity in silicon is about 1020 cm-3. Higher concentrations are usually achieved by combining multiple ion injections into the same substrate. Ion injection also allows for controlled reduction of surface conduction electrons to create a region of space charge within the silicon. This reduces the tendency of electrons to escape from the silicon when it becomes excited by light emission or radiation damage during operation of the device.

Spontaneous generation of electron-hole pairs is the main cause of radiation damage during operation of the device.

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