P-Type Semiconductors

P-Type Semiconductors

Abstract

P-type semiconductors are applied in many sectors of the economy because they are needed in various industries. Innovation in the production of p-type transparent oxide semiconductors that have better performance is essential in the current developing world. Improved semiconductors with complexity in terms of circuit and power efficiency and transparency are needed. Such semiconductors can be applied in electrochromic, memory resistors, photovoltaic cells, sensors, displays, and transparent electronics. Semiconductors made from p-type oxides can be created from materials such as nickel, oxides, spinel oxides, tin monoxide, binary-copper oxides, and Copper bearing oxides. A review of the electronic and crystal structures of the oxides helps show how these types of semiconductors increase mobility and reduce the effective mass of the final products. An analysis of the advancement that has been made in developing oxides in the p-type category also highlights the improvements in electronics industry. Improvement of the semiconductors with p-type denotation has led to an increase in the performance of inverters and thin-film transistors. The development of p-type semiconductors has improved their use in the scientific and technological world.

Introduction

P-type semiconductors are created through the doping of intrinsic semiconductors using trivalent impurities. Since the intrinsic semiconductors have three electrons addition of one more electron will lead to the creation of p-type semiconductors. The electron that is added to the process is shared among the components in the semiconductors. Some of the impurities that are added to make this type of semiconductors include gallium, indium, and boron. The addition of these impurities leads to the creation of germanium or silicon base p-type semiconductors. P-type semiconductors have various applications in the electronic industry, although it has some properties which are undesirable for some uses.

Discussion

Properties of p-type semiconductors

Some of the features that are associated with the semiconductors include:

• Doping of p-type semiconductors is done using trivalent impurities.
• Impurities that are associated with p-type semiconductors are called acceptor impurities.
• Impurities and their atoms have holes in the crystals.
• Electric conductivity for this type of semiconductors takes place because of one hole.
• The application of potential difference on the p-type semiconductors leads to the movement of holes to the negative ends from the positive sides.
• Holes also serve as the leading charge carriers for the p-type electronics.

Applications of p-type semiconductors.

• P-type semiconductors have applications in various electronic devices.
• They are also used in the development of rectifiers that are applied in various electrical components.
• They are also used in the construction of transistors, which are used in the detection and amplification of audio and radio signals.
• They are also used in the development of solar cells, where they are applied in photodiodes to improve light energy conversion into electricity.

Improvement of p-type semiconductors

Although these type of semiconductors has applications in many fields, their application in areas such as those of transparent devices is limited due to low performance compared to n-type semiconductors. Due to the unique properties associated with p-type semiconductors, the improvement of their performance is paramount if its applications are to be increased. Transparent semiconductors are needed due to the increased innovation in the technology industry. Transparency has already started being seen in the smartphone industry with some companies developing ideas about transparent phones. As stated, “Transparent p−n junctions represent a major area where the lack of a wide band gap degenerate p-type material has limited the progress of such devices” (Williamson, et al. 2402). It is for this reason that the improvement of these type of semiconductors should be done. Developing these semiconductors will improve the chances of creating electronic devices that are transparent and perform at high speeds.

The unavailability of p-type oxide high performance semiconductors has limited the development of transparent electronic applications. Transparent semiconducting oxides based on unipolar devices are the only applications that can be put into use currently. High performance semiconductor development for transparent applications using p-type oxides is essential if fabrication of transparent and energy efficient devices is to take place. One of the challenges of developing such types of semiconductors is development of their electronic configuration which is unique and thus difficult to develop. Compared to n-type oxides, they have less vacancies for oxygen which are needed in the production and transportation of electrons through the conduction band minimum made up of metal orbitals (Matsuzaki, et al. 1801968). The spread of these orbitals in n-type oxides allows for the required hybridization to occur which promotes high mobility and low electron mass. This is different from p-type oxides which have limited positive carrier production done by the native acceptors. The production of oil in p-type oxides is limited by the low energy required for the formation of native donors. In cases where holes are available in large concentrations, the valance band maximum usually had localized and anisotropic oxygen orbitals with low mobility and large hole operative mass. These challenges result in the creation of p-type oxides with low performance that are not applicable in many fields.

Transparent conducting oxides have high conductivity of electricity and near perfect optical transparency in ranges within those of visible light. TCOs have been under investigation for some time due to their functions in industries that produce electronics. Such semiconductors are needed in various applications such as organic light-emitting diodes, liquid-crystal displays, solid-state sensors, touch screen displays, and photovoltaic cells (Atahan-Evrenk and Aspuru-Guzik 96). Materials used in the development include SnO_2, ZnO that is mixed AL, flour tin oxide, Sn, and In₂O₃. ITO is credited for its high electrical conductivity combined with great transparency optically at about 80%. All materials used in the development of these oxides are from the n-type transparent conducting oxides. Electronic production prefers the use of n-type TCOs due to their viable electronic properties. Despite the electronic properties that come with n-type, p-type semiconductors have applications in various fields. Its applications are wider functions compared to n-type that are best suited for OLED devices. As stated, “While p-type transparent conducting materials (TCMs) are crucial for many optoelectronic applications, their performance is still not satisfactory” (Zhang, et al. 137). Poor performance by the p-type semiconductors limits their applications but they can be improved so that such characteristics best suite these needs. The changing technological demands have necessitated the need for the creation of transparent semiconductors. Next generation devices are bound to have transparency so that they can satisfy the needs of consumers and increase sales for customers. This demand for such devices is the reason improvement of p-type semiconductors is important.

Another preferred ways of creating p-type semiconductors is through the use of the Chemical Modulation of the Valence Band which is a concept developed by Kawazoe. The implementation of such a concept leads to the gradual improvement of the properties hence achieving qualities such as high performance in electrical activities. Under this concept, the structure of CuAIO₂ which is delafossite in state is used in the preparation of the p-type semiconductors (Yang, et al. 12930). The use of these material is because it has closed shells orbitals that are used in the hybridization of the oxygen orbitals that in turn promote the modification of the valence band modules. This process in turn promotes the delocalization of holes which leads to increased mobility of the holes. The energy from the copper orbitals is in close contact with the oxygen orbitals which in turn promotes the hybridization process (Li, et al. 332). Doping magnesium using the delafossite compound CuCrO₂ in the p-type semiconductor improves the conductivity of the semiconductors. However, this process does not satisfy the transparent properties of the semiconductors. The electronic properties and good work stability that is brought about by the delafossites makes the viable for use in the production of OLEDs. Delafossites lack high transparency and high conductivity which is comparable to the n-type semiconductor oxides. Low conductivity that exists in the p-type semiconductors that have been subject to delafossite injection is due to the polaronic nature and deep acceptor levels that occur in the process. Interband transitions in the delafossites is also one of the reason that these types of p-type semiconductors have low conductivity (Wang, et al. 3832). To increase conductivity of the p-type semiconductors the process of chemical modulation of the valence band using band engineering under copper materials. Band engineering was done using copper materials with the combination of chalcogens (Mönch 182). Semiconductor that are developed using chalcogens have high mobility of holes mainly due to their strong hybridization process compared to the use of oxygen.

Conclusion

Improvement of p-type is essential if they are to get used in more areas and devices. Improvement of these semiconductors can be done using procedures such as Chemical Modulation of the Valence Band and Chemical Modulation of the Valence Band using band engineering. Improvement of the p-type semiconductor oxides will lead to increased application in fields such as photovoltaics, electrochromics, gas sensors, memories, display applications, transparent electronics, and low-power electronics. Improvement of p-type oxides for application in these applications brings about various challenges and developments that limit their commercial application. Application of p-type semiconductors shows better performance in the development of resistive memories with some good performance in transparent materials. The limited application of p-type semiconductors in some fields is because of low mobility of the holes which reduces the performance. Electronics require high performance which is brought about by high electrical conductivity which is most cases is found in n-type conductors. P-type semiconductor development is essential since applications in the technology and electronics industry continue increasing. Different devices and technologies are developed each day due to the changing demand by consumers. For example, the introduction of the internet of things has increased the dependence on electronics that require the use of semiconductors. Hence the improvement of p-type semiconductors is essential if the world is to achieve the high speeds that these devices require.

Works Cited

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