What Is A Semiconductor? How Do Semiconductors Cool?

Semiconductor refrigeration, also known as electronic refrigeration, or thermoelectric refrigeration, is a discipline developed from the 1950s at the edge of refrigeration technology and semiconductor technology. It uses PN junctions composed of special semiconductor materials to form thermocouple pairs and produce Perle The post effect, a new type of refrigeration method through direct current refrigeration, together with compression refrigeration and absorption refrigeration, is called the world's three major refrigeration methods.

Refrigeration principle of semiconductor refrigeration fins

Semiconductor refrigeration film (TE) is also called thermoelectric refrigeration film. It is a kind of heat pump. Its advantage is that it has no sliding parts. It is used in some occasions where space is limited, high reliability is required, and no refrigerant pollution.

The working operation of the semiconductor refrigeration sheet is direct current, which can be used for both cooling and heating. By changing the polarity of the direct current, it is decided to realize cooling or heating on the same refrigeration sheet. This effect is produced by the principle of thermoelectricity, as shown in the figure above. A monolithic refrigeration chip, which is composed of two ceramic sheets, between which there are N-type and P-type semiconductor materials (bismuth telluride). This semiconductor element is connected in series in the circuit. The work of the semiconductor refrigeration sheet The principle is: when a piece of N-type semiconductor material and a piece of P-type semiconductor material are connected to form a galvanic pair, after the DC current is connected in this circuit, energy transfer can occur, and the current flows from the N-type element to the joint of the P-type element It absorbs heat and becomes the cold end. The P-type element flows to the joint of the N-type element and releases heat, which becomes the hot end. The magnitude of heat absorption and heat release is determined by the magnitude of the current and the number of pairs of semiconductor materials N and P elements. The inside of the refrigeration sheet is a thermopile formed by hundreds of electric couplings to achieve the effect of enhanced refrigeration (heating).

 What is a semiconductor?

Semiconductor refers to some materials with controllable conductivity. This kind of electronic material is a material that can conduct electricity at room temperature, but semi-conductor cannot be called a conductor completely because it can also become an insulator under certain conditions. Due to these characteristics of semiconductors, it will be used in electronic equipment such as radios and televisions. When the machine is overheated, it can play a role in refrigeration and prevent the overheating of other parts from burning. The survey found that many home appliances and work tools used by people now contain semiconductor materials.

The performance of semiconductor materials

Semiconductor is not a specific material. It exists in various forms. At the same time, because of its different forms, semiconductor materials have more properties.

1. Elemental Semiconductor

This type of semiconductor refers to the use of a certain element, and the representative ones are silicon and tin. These elements can form solid materials with semiconductor characteristics, and are also very susceptible to external influences. Once mixed with other impurities, they will change. Since tin is composed of less effective semiconductor materials, silicon and germanium are two of the most common elements currently on the market. Silicon is widely used in industry, and silicon dioxide is produced during use. This substance can form a protective film and can greatly promote the stable operation of components.

2. Organic compound semiconductor

This kind of semiconductor refers to the structure containing a certain carbon bond compound, and the conduction band can be formed by superimposing the organic compound and the carbon bond vertically. The conduction band is introduced into the energy band by means of chemical addition, so that electrical conductivity can occur, so that organic compound semiconductors can be formed. Since this type of semiconductor is composed of organic compounds, it has a certain degree of solubility and the processing method is relatively simple, which can help companies save costs to a large extent. This kind of semiconductor controls its own conductivity by controlling molecules, so it is mostly used in the fields of organic thin film and organic lighting.

3. Amorphous semiconductor

Because its appearance is similar to glass, it is called glass semiconductor. Amorphous semiconductors have the same characteristics as other amorphous materials. In most cases, it exists in a structure of short-range order and long-range disorder. The main element is silicon, which is amorphous silicon by changing the position of atoms. At the initial stage of semiconductor development, amorphous semiconductors are one of the more difficult to control, but with the continuous development of technology, this type of semiconductor has also been widely used. Because of its own light-absorbing characteristics, it will be applied to solar energy. Among the batteries and the LCD screen.

Types of semiconductor refrigeration systems

1. Air convection heat dissipation

This kind of heat dissipation method is more similar to the usual fan heat dissipation, which blows away the heat generated by the parts through air flow, so that it can achieve the purpose of cooling down. The use of air convection to dissipate heat will be affected by many factors. First, the heat sink has heat conduction performance, which can transfer the heat emitted by the parts as soon as possible to make it contact with the air and realize heat dissipation. Second, when the air flow speed is faster, the heat dissipation speed can be increased. Therefore, during the installation of the related system, an additional fan must be installed to ensure that the air flow speed can meet the highest requirements. Third, the temperature of the air itself has a greater impact on the heat dissipation, and the heat dissipation effect will be poor in summer.

2. Water cooling

This method is widely used at present. The liquid cold plate uses the circulating flow of cooling liquid to realize heat dissipation, and most of the heat generated by the parts can be taken away during the flow process. Compared with the air heat dissipation effect, this method will be more obvious, and no noise will be generated during the heat dissipation process. In addition, for some devices with strong heat production, fans will be added to improve the heat dissipation effect. Therefore, it is mainly used in components such as power supplies and water pumps.

3. Heat pipe cooling

The heat pipe is a metal tube body that can quickly reduce the temperature of the component to a constant temperature. The heat pipe heat sink is mainly composed of liquid working fluid, tube core, tube shell and other parts. This structure enables the liquid in the tube to perform a variety of circulating flows, so as to transfer heat, volatilize heat, and realize heat dissipation. The liquid working fluid of the heat pipe has good thermal conductivity, boiling point, and low viscosity, so it can be circulated continuously to realize heat conduction. In order to meet the needs, the tube core is set to imitate the human capillary wall, and the inside is mostly a capillary structure, so it can not only achieve rapid and large-scale heat conduction, but also reduce thermal resistance. Since the heat pipe is in a closed space during the working process, it can just generate a pressure for the circulation of the liquid working medium to promote its work.

Concluding remarks

In summary, after this analysis, we can have a more accurate understanding of the various properties and types of semiconductors. And can understand the heat dissipation method suitable for various projects and equipment. However, in recent years, with the continuous emergence of the greenhouse effect, the development of various refrigeration equipment has received attention from all walks of life. For this reason, it is necessary to conduct in-depth analysis of semiconductors and develop more effective cooling and heat dissipation systems to promote better development of enterprises.