What is an semiconductor?
From the 1950s around the beginning of the emergence of the first generation of semiconductor materials, silicon and germanium, etc.; to about a decade after the emergence of the second generation of semiconductor materials, gallium arsenide, indium phosphide, etc.; and then to the 1980s when the third generation of semiconductor materials, gallium nitride, zinc oxide, aluminum nitride, silicon carbide, etc. now.
This iteration and evolution are going in one direction, that is: higher energy conversion efficiency, higher operating temperature and operating frequency, higher reliability and stability, lower cost and higher productivity.
Part 01 LED
Semiconductor optoelectronic devices are functional devices that utilize the light-to-electricity conversion effect, which means that these devices can achieve a variety of functions through the conversion and control of light and electricity. Its main representatives are LED (light-emitting diode), LD (laser diode) and photodetectors and so on. These devices can be found everywhere in our lives, such as displays, lights, remote controls, scanners, fiber optic communications and other fields have a wide range of applications.
A said LED, we basically know, is not a light-emitting diode well! LED is a semiconductor device that can convert electrical energy into visible light, they can emit a variety of colors of light, and has a small size, long life, low energy consumption, colorful features. The displays, lighting, traffic signals, etc. that we see are the most basic applications of LEDs.
If the LED is the "body", then the LED chip is its "heart". LED chip is the core component of the LED, is a semiconductor wafer, one end of the wafer is attached to a bracket, one end is the negative pole, the other end is connected to the power supply positive pole, so that the whole wafer is encapsulated by epoxy resin. The LED chip needs to be encapsulated, tested and sorted before it can become a usable LED product.
There are many different types of LED chips, such as ordinary LEDs, OLEDs, MiniLEDs, MicroLEDs, etc., which have different performances and characteristics according to different light-emitting principles and structures, and are applicable to different fields.
LED chip is the most core and highest value-added link in the LED industry chain, and it is also the key factor affecting the performance and quality of LED. With the continuous development and innovation of LED technology, LED chips are also improving their efficiency, brightness, stability and reliability to meet the market demand for higher performance and lower cost.
Let's talk about LD, people who have heard of this may be relatively few, but in fact it is a semiconductor laser device. LD (Laser Diode) is a semiconductor device capable of generating lasers, which can emit monochromatic, unidirectional, coherent light, with a small size, high efficiency, modulation is easy, the wavelength can be adjusted. We often talk about fiber optic communication, laser printing, laser cutting, etc., are LD applications.
Semiconductor Laser Components
LDs are also divided into many different types, such as non-communication laser chips and optical communication laser chips, which are used in different scenarios according to different operating wavelengths and powers.
Photodetectors we have contact with can be a lot, you use to monitor the family kittens and small dogs and children's camera is a typical photodetector applications, in addition there are scanners, remote controls, solar cells, and so on, many commonly used devices there are photodetectors of the figure.
Photodetector is also through the conversion of light energy into electrical energy to achieve a variety of functions of the semiconductor device, they can detect a variety of intensity and wavelength of light, and will be converted to current or voltage, so as to convey the corresponding electrical signals. For example, PIN diodes, APDs (avalanche diodes), CMOS image sensors (CIS), etc. all belong to the category of photodetectors.
Optoelectronics is a large field, and optoelectronic devices play an important role in our lives and promote the progress and innovation of science and technology. With the continuous development of semiconductor technology, semiconductor optoelectronic devices may present more new forms and novel functions.
Part 02 Power Semiconductor Devices
Power semiconductor devices are made of power semiconductor materials. Power semiconductor materials have wide bandwidth, high breakdown field, high thermal conductivity, high electron mobility and other characteristics, can work in high temperature, high voltage, high frequency, high power and other extreme conditions, to achieve effective conversion and control of electric energy.
Power semiconductor devices can be divided into power semiconductor discrete devices (Power Discrete, including power modules) and power semiconductor integrated circuits (Power IC) two categories. Therefore, power semiconductor discrete devices are actually a subcategory of power semiconductor devices.
Power semiconductor discrete device is specified to complete a certain basic function, and itself in the function can not be subdivided semiconductor devices, according to its structure and function, can be divided into power MOSFETs, IGBTs, power diodes, power bipolar transistors and thyristors (thyristors) 5 major types.
MOSFETs, diodes, bipolar transistors have been introduced in the previous article, here to talk about IGBTs and thyristors.
IGBT (Insulated Gate Bipolar Transistor), the full name of the insulated gate bipolar transistor, is a voltage-driven composite device, composed of MOSFET and bipolar transistor, the input part of the MOSFET structure, the output part of the bipolar structure. Therefore, it combines the advantages of both, featuring high input impedance, strong current amplification, low on-resistance and high voltage withstand.
The switching characteristics of IGBT can realize the conversion between DC and AC or change the frequency of current, which has the function of inverter and frequency conversion. It is extremely suitable for medium-high frequency, medium-high voltage, high-power AC/DC conversion and frequency conversion applications, such as inverters, frequency converters, switching power supplies, lighting circuits, traction drives and so on. It is precisely for this reason that IGBTs are used in a large number of emerging applications from small home appliances and digital products to aerospace and high-speed rail, as well as new energy vehicles and smart grids.
Silicon Controlled Rectifier (Silicon-Controlled Rectifier, SCR) is a current-driven semi-controlled semiconductor device, also known as bi-directional silicon controlled. It consists of two bipolar transistors (i.e., four alternating P-type and N-type semiconductor layer), with high voltage, high allowable current, high reliability and other advantages, suitable for low-frequency, high-voltage, high-power AC control and rectification applications, such as controllable rectifier power supply, AC speed control circuit. Based on its own unique electrical characteristics (bi-directional conductivity and controllability), SCR has become an important component in the field of electronics and power applications.
As for power semiconductor integrated circuits, it actually refers to semiconductor devices that integrate power semiconductor discrete devices with peripheral circuits such as drive/control/protection/interface/monitoring, e.g., IPMs, SiC power devices, power management chips, driver chips, and so on.
In general, the special feature of power semiconductor devices is that they have the ability to handle high voltage and high current, can work in special environments, and can achieve high switching speed and efficiency, with only low switching loss and conduction loss, while also ensuring high reliability and stability.
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