Semiconductor Materials: Electrical and Magnetic Properties - Case Study Example

Name: Institution: Instructor: Subject: Date: SEMICONDUCTOR MATERIALS: ELECTRICAL AND MAGNETIC PROPERTIES Abstract The content of this document offers a description of the materials used as semiconductors with regard to their electrical and magnetic properties. It indicates the factors that influence their electrical and magnetic proper ties when subjected to various conditions. Semiconductors are described as useful components in the electrical and electronic industries. The fact that the nature of semiconductor’s material electrical conductivity greatly depends on the level and type of impurities, these dependency can be modified in a manner that provides paths, channels as well as junctions. This level of control in the semiconductor materials permits the creation of several variations in terms of voltage and current characteristic as well as their control means. Semiconductor materials with regard to both the electrical and magnetic properties are used in the manufacture of devices such as power transistors and semiconductor switches. Introduction The classification of semiconductor materials with regard to the electrical properties takes into consideration the materials’ solid state. The materials are generally classified in accordance with their conductivity of the electrical charges. The conductivity of the semiconductor materials exists between that of conductors and insulators. Semiconductor materials have got great variability with regard to their conductivity. Pure state semiconductors could possess conductivities as high as twelve magnitude orders lower than that of copper. This comparison makes the semiconductor to appear to be more of an insulator than a conductor. The presence of small amounts of impurities in the semiconductor materials however, may reduce the effectiveness of their conductivity [1, 2]. Furthermore, the kind of conductivity that is possessed by semiconductors has a lot of sensitivity to temperature, illumination, electrical field, magnetic field as well as the availability of cognitive processes. This sensitivity level causes the semiconductor to be regarded as a very important material in the industry of electrical engineering. Semiconductors in their purity are strongly affected by temperature and are highly sensitive to temperature. The levels of trace impurities in semiconductor materials cause a limitation to the thermistor performance and increase the features to a strong extent. Even though it might appear that that semiconductor materials having higher sensitivity to the impurity materials have got limited uses, the semiconductor obtains its immense quality and value from such ambivalent qualities. The developments in the technology of materials have permitted the engineering industry to apply the use of such materials in the channeling and control of electrical fields and currents. Since semiconductor materials are regarded as poor conductors of electricity, they can be able to permit charge separating and the blockage of the localized E-fields [1-3]. The conductivity nature of a semiconductor material allows it to sustain the electrical transportation of mobile carriers that are charged. Electrical properties of semiconductor materials Semiconductors exists in the form of polycrystalline or simply crystalline. This is the case whether the material is germanium, silicon, indium or gallium-arsenide. When the joining of atoms takes place in a group of molecules, the sharing of energy levels occurs and there are preferences of separate energy levels that are slightly different. Atoms in their state of crystals are organized into an array of large scale that extends infinitively in all directions. Due to this large extent of sharing, the state of energy of individual atoms are considerably smeared and spread out in the process of slight differentiation. The rearrangement of energies has a tendency of occurring groupings of parity which are referred to as the energy bands [1, 2, 4-7]. Figure 1: States of bonding and anti-bonding states Electronic crystal structure of semiconductor materials There is limited consideration in the semiconductor electronic atom structure as well as the creation of covalent bonding that exists with the atom pairs. Solid crystals are a bit bigger wit extensions of assemblage atoms. Nonetheless, the principles of quantum mechanics with regard to the electrical properties of semiconductor materials remain the same without changing for the extended entire crystals. For silicon the case can be illustrated as shown below [3]; Figure 2: Illustration of Silicon crystal with regard to energy band information Intrinsic Semiconductor bands For the semiconductor materials with regard to the electrical properties, the structures of the band for the actual crystalline is a bit complex and permit a wide variety of differences in features. Germanium and silicon are believed to exhibit semiconductor band gap that are indirect whereas the gallium arsenide exhibits direct semiconductor band gap. In direct semiconductor band gap, the promotion of an electron can take place from the band of valence to the band of conduction in a direct manner without necessarily experiencing or going through changes in in the momentum such as the photon absorption. In the physical state, this takes place due to energy band curvature and alignments that are favorable [1, 4-7]. Conversely, there is an indirect semiconductor energy band gap with similarity in the electron promotion from the band of valence electrons to the bad of conduction that has to interact with the lattice of the crystal so as to satisfy the conservation momentum principle. The alignment of the corresponding band becomes unfavorable. It is therefore important to note that the differences that exist between the indirect and direct band gap in semiconductor materials with regard to their electrical properties is not very significant for the operation of conventional electronic devices. However, this technology is regarded as being very important for the electronic devices that are involved in light emission and distribution such as the laser diodes and light emitting diodes. [1,2,4-7]. The electrical conductivity that is exhibited by a semiconductor material in its pure form is usually very low. This is owing to the fact that the electron movement in the valence band is also taking place at a very low rate. This may be regarded as a natural outcome of the valence electron participation in the crystal lattice bonding. This participation requires electron pair localization that takes place within the atomic nuclei. A dramatic increase in the electrical conductivity of a pure semiconductor is evident when the promotion of electrons take place from the valence band to the band of electron conduction since the electron since the conduction band are free to move about in this band than in the valence band. The density of the electrons is considerably less for the localized bands as compared to the valence bands. The electron that is present in the band of conduction leave holes behind in the semiconductor band of valence which is then reviewed in the process of sorting an electron with a positive charge [2, 4-7]. Within the crystal structure of a semiconductor material, both the holes and electrons are regarded as particles that are distinct and are able to serve as carriers with opposing electrical charges. Carrier mobility The electrical properties of semiconductor materials are fundamentally influenced by the energy band structure. This takes into consideration the electron that is located in potentials that are varying periodically. The quantum theory is use in the prediction of the energy zones and locations that that are occupied by electrons. In crystals of semiconductor materials the wave of the electron diffracts out of the atoms in the same way that the x-rays also diffract from atoms. The conductivity of semiconductor is dependent upon mobility and carrier density. The carrier density is a function of the type of semiconductor material, doping and temperature whereas mobility is a function as the type of semiconductor, temperature and impurity density [4, 7]. The electrical properties of the semiconductor material involve the mobility of carrier whereby the rise in temperature causes a decrease in mobility as a result of vibrations in lattice. The impurity scattering in the semiconductor materials brings about a reduction in mobility with doping. Figure 4: Graphical illustration of carrier mobility Electrical behavior of semiconductor pn-Junctions The consideration of the happenings s in the semiconductor materials with regard to the electrical properties of pn-junctions involves performance of experimentation activities. Two semiconductor block materials with extrinsic doping that s opposing each other, i.e. a p-type block and an n-type block at first are widely separated. When the joining of these blocks takes place, a net carrier transfer is witnessed from one of the blocks to the other block. This takes place so as to realize the establishment of equilibrium [1, 2- 7]. This is a case that can be compared to situations that occur in the contact between a semiconductor metal and a capacitor. When the entire system attains equilibrium, the Fermi level is expected to remain constant in the whole combination of volumes for the two blocks that are involved. In this process it is a requirement that the bending of conduction ad valence bands takes place at the junction region. The illustration of this situation is ass shown; Figure3: pn-junction electrical band diagrams The determination of the junction position is made at the point of intersection between the actual Femi and the intrinsic level of Femi. This brings about the definition of the exact point on which the semiconductor material with regard to its electrical properties experiences change from one state to another different one. This is otherwise referred to as the intrinsic that is occurring at the junction. Even if there is hypothetical construction of the structure through the coming together of different blocks of semiconductor materials, the physical principle mechanism that is used in the formation of pn-junctions is immaterial as far as its electrical behavior is concerned [1-4]. Magnetic properties of semiconductor materials The magnetic properties of semiconductor materials are mostly described through the semiconductor alloys. A widely known compound of antiferromagnetic semiconductor material undergoes transformation and becomes an alloy ferromagnetic o n-type. This king of transformation is guided by an interaction that takes place through the electrons that are involved in conduction and are also formulated as a result of substitution of various ions. With regard to the elevated degrees of the polarization of electron spin, the magnetic properties of semiconductor materials can be exploited to come up with various structures. The measurement and analysis of magnetization and magnetic susceptibility has been able to show that the relationship between ferromagnetic and temperature [1, 2, 4]. The magnetization analysis performed on a wide range of magnetic properties of semiconductor materials whose applications are made in several crystal directions, has been able to reveal rapid ferromagnetic responses. Europium telluride comes from a properly known category of semiconductors with magnetic properties as well as antiferromagnetic material model. The materials reveal a unique feature with regard to the possibility of it transformation from insulation of antiferromagnetic semiconductor material to an n-type semiconductor material through the substitution of Gd3+ ions with Eu2+ in the matrix structure of crystal [1,4-7]. The mechanism that is employed in transformations of that nature find its attribution to interactions of Ruderman–Kittel. That is the coupling that is in existence between mediated spins that are strongly localized. According to studies previously carried out with regard to bulk semiconductor materials, it has been demonstrated that concentrations that reach the extent of 60% for (Eu,Gd)Te crystals in the materials are able to indicate transitions that are ferromagnetic , whereas for concentration that go beyond 60% especial with regard to (Gd), there are changes experienced in the magnetism type [1,2,4-6]. Figure 5: Magnetic susceptibility if AC in comparison to temperature of ferromagnetic and antiferromagnetic semiconductor materials In accordance with the mechanism described above, a lot of europium-gadolinium chalcogenides having the presence of Gd content lower than 60% is established as ferromagnetic semiconductors. These categories of semiconductors exhibit magnetic properties at Curie temperatures that are over 150K when oxides are considered and 0K when tellurides are considered. The (gadolinium chalcogenides) which are terminal alloys in semiconductor materials are regarded as antiferromagnetic compounds having a conductivity of metallic type. When the ferromagnetic state of semiconductor materials are considered, the n-type (Eu,Gd)Te shows polarization of elevated electron spin in relation to a huge splitting in the states of conduction band. This characteristic combined with the anticipated compatibility behavior of (Eu,Gd)Te with widely available materials of nonmagnetic semiconductors like PbTe causes (Eu,Gd)Te to become a major elements that intrigues. This is especially the case when it comes to semiconductor materials that are new and are involved in spin injections. Experimental research studies have been able to reveal that the magnetic properties of semiconductor materials especially those of the epitaxial layers belonging to (Eu,Gd)Te are presented and can be observed on the basis of stoichiometric cry state of the alloy. The layers of (Eu,Gd)Te in the semiconductor materials are mostly exhibited in systems that harbor effusion cells as well as solid sources [1,2,4-7]. Conclusion In conclusion, both the electrical and magnetic properties of semiconductor materials are key consideration in the design and operation of electronic components and devices. These devices utilize direct semiconductor band gap in the course of their functionality. For several practical cases, the details of band structure are not greatly significant and are often simplified into categories of two aggregate semiconductor bands. These are the conduction and valence bands. Similar to the situation of molecular or atomic orbitals, electrons in the crystal structure of a solid are expected to satisfy the principle of electrical and magnetic operations. Therefore overlooking any of the effects brought about by the existence of thermal of photo excitation in, the semiconductor valence band could be considered as a wholly filled whereas the conduction band is wholly empty. It is therefore important to consider the properties of the semiconductor materials in the analysis of the electronic components and devices. References 1. A. Muhammed, S.O. Amiebenomo. Control Theory and Informatics. 3, 2013, 31. 2. D.S. Datar, N.E. Chimelu. Journal of Information Engineering and Application. 3, 2013, 24. 3. F.Zarzoura, E.A. Mazandarani, H. Moneni. Computer Engineering and Intergrated Systems. 4, 2013, 46. 4. G, Micard, G. Hahn, A. Zuschlag, S, Seren, S. Terheiden. Journal of Applied Physics. 108, 2010, 345. 5. M.A. Caro, S. Schulz. Journal of Physics: Condensed Matter. 25, 2013, 13. 6. S.Mahdi, Y.Chen, H. Bada. Advnaces in Physics theories and Applications. 25, 2013, 36. 7. Y. Kajikawa. Journal of Applied Physics. 114, 2013, 321. Read More

Since semiconductor materials are regarded as poor conductors of electricity, they can be able to permit charge separating and the blockage of the localized E-fields [1-3]. The conductivity nature of a semiconductor material allows it to sustain the electrical transportation of mobile carriers that are charged. Electrical properties of semiconductor materials Semiconductors exists in the form of polycrystalline or simply crystalline. This is the case whether the material is germanium, silicon, indium or gallium-arsenide.

When the joining of atoms takes place in a group of molecules, the sharing of energy levels occurs and there are preferences of separate energy levels that are slightly different. Atoms in their state of crystals are organized into an array of large scale that extends infinitively in all directions. Due to this large extent of sharing, the state of energy of individual atoms are considerably smeared and spread out in the process of slight differentiation. The rearrangement of energies has a tendency of occurring groupings of parity which are referred to as the energy bands [1, 2, 4-7].

Figure 1: States of bonding and anti-bonding states Electronic crystal structure of semiconductor materials There is limited consideration in the semiconductor electronic atom structure as well as the creation of covalent bonding that exists with the atom pairs. Solid crystals are a bit bigger wit extensions of assemblage atoms. Nonetheless, the principles of quantum mechanics with regard to the electrical properties of semiconductor materials remain the same without changing for the extended entire crystals.

For silicon the case can be illustrated as shown below [3]; Figure 2: Illustration of Silicon crystal with regard to energy band information Intrinsic Semiconductor bands For the semiconductor materials with regard to the electrical properties, the structures of the band for the actual crystalline is a bit complex and permit a wide variety of differences in features. Germanium and silicon are believed to exhibit semiconductor band gap that are indirect whereas the gallium arsenide exhibits direct semiconductor band gap.

In direct semiconductor band gap, the promotion of an electron can take place from the band of valence to the band of conduction in a direct manner without necessarily experiencing or going through changes in in the momentum such as the photon absorption. In the physical state, this takes place due to energy band curvature and alignments that are favorable [1, 4-7]. Conversely, there is an indirect semiconductor energy band gap with similarity in the electron promotion from the band of valence electrons to the bad of conduction that has to interact with the lattice of the crystal so as to satisfy the conservation momentum principle.

The alignment of the corresponding band becomes unfavorable. It is therefore important to note that the differences that exist between the indirect and direct band gap in semiconductor materials with regard to their electrical properties is not very significant for the operation of conventional electronic devices. However, this technology is regarded as being very important for the electronic devices that are involved in light emission and distribution such as the laser diodes and light emitting diodes.

[1,2,4-7]. The electrical conductivity that is exhibited by a semiconductor material in its pure form is usually very low. This is owing to the fact that the electron movement in the valence band is also taking place at a very low rate. This may be regarded as a natural outcome of the valence electron participation in the crystal lattice bonding. This participation requires electron pair localization that takes place within the atomic nuclei. A dramatic increase in the electrical conductivity of a pure semiconductor is evident when the promotion of electrons take place from the valence band to the band of electron conduction since the electron since the conduction band are free to move about in this band than in the valence band.

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