-------------------Semiconductor is the basis of informationization-------------------
The invention of semiconductor large-scale integrated circuits, semiconductor lasers, and various semiconductor devices in the last century has played a vital role in the modern information technology revolution, triggering a new global industrial revolution.
Informatization is the general trend of economic and social development in the world today. The level of informatization has become an important indicator to measure the modernization of a country and region.
In the 21st century, the world is accelerating the pace of information construction.
Due to the needs of the information technology revolution, semiconductor physics, materials, and devices will have new and faster development.
The size of integrated circuits will become smaller and smaller, and new quantum effect devices will emerge. Wide bandgap semiconductors represent a new direction and will have broad applications in short-wavelength lasers, white light-emitting diodes, high-frequency and high-power devices. Nanoelectronic devices are likely to be the next generation of semiconductor microelectronics and optoelectronic devices; the use of single-electron, single-photon and spin devices as quantum modulation will play a key role in the practical application of quantum computing and quantum communication.
-------------------Transistor invention-------------------
At the end of World War II in 1945, Barclays, president of Bell Labs, decided to set up a solid-state physics group to adapt to the needs of the room from wartime to peacetime. Raton, Gibney, Moore and others.
Shockley and Badin are theoretical physicists, Bratton is an experimental physicist, Gibney is a physical chemist, and Moore is a circuit scientist. This combination of professionals is a semiconductor physics research and invention of transistors. It is a golden match, lean and efficient. Based on their experience and subsequent considerations since the mid-1930s, they focused on the research of silicon and germanium in semiconductor materials from the very beginning.
During the Second World War, the British used radar to detect German bombers. At the heart of the radar is a vacuum tube that amplifies the weak current. As early as 1939, Shawley was preparing a solid device capable of amplifying current to replace the vacuum tube. In December 1947, Badin and Bratton made the world's first point-contact triode with current amplification.
The results of Badin and Bratton were published in June 1948. Although the invention of the point contact transistor has unveiled the prelude of the great development of the transistor, due to its complicated structure, poor performance, large size and difficulty in manufacturing, it has not been popularized and applied by the industry, and the response caused by the society is not strong enough.
In January 1948, Xiao Clay invented another junction-type transistor based on his own research on the p-n junction theory, and obtained a patent in June 1948. A junction transistor, also known as a field effect transistor, is planar (see Figure 3) and can be mass produced by planar processes such as diffusion, masking, etc. Therefore, only after the invention of the junction transistor, the superiority of the transistor is well recognized and gradually replaced the vacuum tube.
In 1956, the Nobel Prize in Physics was won by Badin, Bratton and Shockley for their contributions to the invention of transistors and junction transistors. The first application as a semiconductor transistor was Sony's portable radio, which swept the world and made a lot of money.
-------------------Invention of integrated circuits-------------------Transistor radios are much smaller than tube radios and can be carried around. However, it is soldered to a circuit board by transistors, resistors, capacitors, and magnetic antennas, and connected to each other by wires. The volume is still relatively large and the assembly process is complicated.
In 1958, the US government set up a transistor circuit miniaturization fund to adapt to the needs of the United States to catch up with the first satellite launched by the former Soviet Union. At that time, Kelby of Texas Company took on this task, trying to make miniaturized circuits that packaged transistors, resistors, and capacitors together.
In September 1958, Kelby made the world's first integrated circuit oscillator, all of which was recorded in his notes of the day. The integrated circuit invented by Kilby was patented in February 1959 under the name "Miniature Electronic Circuits".
At the same time, Neuss of Fairchild Semiconductor, Calif., proposed the idea of connecting transistors with aluminum. Five months after Kilby invented the integrated circuit, in February 1959, he used the planar transistor method proposed by Holni to generate a SiO2 mask on the entire silicon wafer, and applied a lithography technique to form a window and a lead according to the template. The via, diffuses impurities through the window, constitutes a base, an emitter, and a collector, and evaporates gold or aluminum, thereby forming an integrated circuit. In July 1959, Neuss's integrated circuit was patented under the name "Semiconductor Device and Lead Structure". Since then, the integrated circuit has embarked on a new era of large-scale development.
-------------------Invention of solar cells-------------------In 1954, Pearson and Fuller used a diffusion technology of phosphorus and boron to make a large-area silicon pn junction solar cell with a photoelectric conversion efficiency of more than 6%, exceeding the best solar conversion efficiency in the past. 15 times. It is inexpensive to produce and can be mass-produced, so it is quickly getting a large-scale application.
The working principle of solar cells is the photovoltaic effect. When light is irradiated on the semiconductor, electron-hole pairs are generated in the semiconductor. If the external circuit is turned on, current will pass, which is the photovoltaic effect.
The commercial application of solar cells began in 1958 and was selected as the power source for the radio transmitter of Vanguard I, the first satellite in the United States. Under the current energy crisis, solar cells have attracted great attention as a kind of regenerative and pollution-free power source.
-------------------Invention of semiconductor laser-------------------The working principle of semiconductor light-emitting tubes and lasers is exactly the opposite of solar cells: solar cells use electricity to generate electricity, while light-emitting tubes and lasers use electricity to generate light. Electrons and holes are introduced into the conduction and valence bands of the semiconductor, respectively. Electrons and holes recombine to produce photons.
In 1962, Hall of America made the first semiconductor laser with a p-n homojunction. The laser must be generated in three conditions: the inverse distribution of the number of particles, the cavity and current exceed a certain threshold.
In 1963, Klemer in the United States and Alferov in the Soviet Union independently made heterojunction lasers. In Figure 8, the junction region used a material with a small band gap, such as GaAs; The zone and n zone use another material with a large forbidden band width, such as AlxGa1-xAs. Thus, the light-emitting area is confined in the narrow junction area.
Therefore, the luminous efficiency is greatly improved and the threshold current of the laser is lowered. In 1970, the Soybean Institute of the Soviet Union and the Bell Labs of the United States respectively made double-heterojunction lasers that operated continuously at room temperature, making semiconductor lasers widely used in optical communication.
Thanks to Klemer and Alferov's important contributions in the development of semiconductor lasers, they won the Nobel Prize in Physics in 2000 together with IC inventor Kirby. The invention of silicon LSIs and semiconductor lasers has enabled the world to enter an information age based on microelectronics and optoelectronics, which has greatly promoted social and economic development.
-------------------Invention of molecular beam epitaxy-------------------A key technique for fabricating double heterojunction lasers is molecular beam epitaxy. In 1968, Bell Labs discovered that molecular beam epitaxy was invented by finely controlling the size and time of the beam in an ultra-high vacuum vessel to grow different layers and different types of semiconductor materials as needed. A schematic diagram of a molecular beam epitaxy apparatus is shown in FIG.
The inside of the device is under ultra-high vacuum conditions (10-10 torr), and the source of the raw material elements (such as Ga, As, Al, etc.) is contained in the evaporation furnace. The front is a controllable baffle that opens the baffle and directs the evaporated source atoms onto the heated substrate for epitaxial growth. At present, the growth of a single atomic layer has been achieved by this technique. Around the device are some testing instruments to monitor the growth process.
