Department of Physics, Hong Kong Baptist University
Semiconductor materials have been studied in laboratories as early as 1830. The first materials studied were elements and compounds, which are poor conductors if heated. However, when light is shine on them, it would generate an electrical current that could pass through them in one direction only. This means we can control the direction of flow of electricity. Another example, radio receivers required a device called a rectifier to detect signals. Ferdinand Braun used the rectifying properties of the galena crystal, a semiconductor material composed of lead sulfide, to create the cat's whisker diode. The rectifying properties create a voltage potential between the metal contact and the semiconductor such that electrons would ‘slide’ down the potential when going in one direction, but need to ‘climb’ up the potential in the opposite direction. Thus the first semiconductor device was produced.
By 1874, electricity was being used not only to carry power, but also to carry information. The telegraph, telephone, and later the radio were the earliest devices in the industry that would eventually be called electronics.
In the first half of the 20th century, The electronics industry was dominated by vacuum tube technology, but they were fragile, bulky, unreliable, power hungry, and produced considerable heat. Vacuum tube is in fact a glass tube which has its air inside evacuated, and it has positive, negative electrodes so that electrons move from the cathode to the anode. To encourage the electrons to do that, the cathode is heated to high temperature (at least a few hundred degree Celsius) so that electrons got so hot that they ‘jump’ out of the cathode. A way to control the flow of electron is using a third electrode, called grid. This is slightly more negative than the cathode so it can retard the electrons by varying its potential. It was not until 1947, with the invention of transistor by Bell Telephone Laboratories, that the vacuum tube trouble was solved. Transistor is like solid state equivalent of vacuum tube, with no vacuum and glass tube; electrons move from cathode to anode (they are called source and drain now) and the electron flow is controlled by a gate which acts similar to the grid in vacuum tube. In Compared to vacuum tube, transistors were smaller, more durable, reliable, consume less power and produce less heat. Transistor allows engineers to design more complex IC circuits and equipment comprising hundreds or thousands of discrete components such as diodes, capacitors, rectifiers and transistors. This creates another problem; these components still have to be interconnected to constitute electronic circuits, and to hand-solder thousands of components to thousands of bits of wire is costly and time-consuming. It is unreliable too; soldered joint can fail and therefore every joint can be a potential source of problem. The challenge is to search for cost-effective and reliable ways of producing and interconnecting these components.
(common diode nowadays)
(common LED nowadays)
The Integrated Circuit Packaging each component (transistors, resistors, and capacitors) and hand wiring the components into circuits were extremely inefficient. The USA military began to look for more efficient way to make electronic circuits. One of the solutions was the Micro-Module program sponsored by the U.S. Army Signal Corps. The concept was to make all the components in uniform size and shape, with the wiring construct into the components. Then, the modules could be snapped together to form circuits, eliminating the demand for wiring the connections. It means that resistors, capacitors, transistors all have the same size, just like Lego and you snap them together to form a circuit of your design.
(Jack Kibly's IC - picture is provided by Texas Instruments Semiconductor Asia)
Texas Instrument was working on the Micro-Module program when Jack Kilby joined the company in 1958. Because of his work with Centralab in Milwaukee, Kilby was familiar with the problem faced by the industry. However, he did not think the Micro-Module can solve the basic problem of large quantities of components in complex circuits (imagine what happens if you are designing a large and complex circuit like a computer processor!). Therefore Kilby commenced searching for another options and in the process decided the only object a semiconductor house could make cost effectively was a semiconductor. Moreover, he commenced to write down and sketch out his idea in July of 1958, when everyone else had left for the annual two-week vacation. It was in a deserted laboratory at Texas Instrument's brand new Semiconductor Building where Jack Kilby first hit on the idea of the integrated circuit. By September, he has a working integrated circuit built on a piece of semiconductor material. On September 12, 1958, several executives of Texas Instrument, including the former Chairman Mark Shepherd, gathered for the demonstration given by Kilby. They saw a sliver germanium, with protruding wires, glued to a glass slide. It was a rough device, but when Kilby pressed the switch, a sine curve appeared across the oscilloscope screen, it was a simple oscillator circuit. His invention operated successfully. That means he had solved the problem. In the year 2000, Jack Kilby, the inventor of integrated circuit, became one of the recipients of the Nobel prize in Physics.
(will be presented in link of video)
http://www.ti.com/corp/docs/kilbyctr/graphics/jack3.avi In 1959, Jean Hoerni and Robert Noyce, who later founded Intel, developed a new process called planar technology at Fairchild Semiconductor which enabled them to diffuse various layers onto the surface of a silicon wafer to make a transistor, leaving a layer of protective oxide on the junctions. This process allowed metal interconnections to be evaporated onto the flat transistor surface and replaced the hand wiring. The new process used silicon instead of germanium, and made commercial production of ICs possible. The initial resistance to the new IC technology gave way to enormous popularity. By the end of the 1960s, nearly 90% of all the electronic appliances were products of integrated circuits. Now we have more than one million transistors on a single computer chip!
The impact of Kilby’s tiny chip go beyond anyone’s imagination at that time. Nowadays, many of the electronics products could not have been developed without it. From the small chip that Kilby built, modern computer industry raised. Those room-size machines built in 1940s and 1950s are transformed into today’s array of mainframes, minicomputers, personal computers and personal digital assistant. The chip restructured communications, created a plethora of new ways for instant exchanges of information between people, businesses and nations. In fact, human beings could not explore space or land on the moon without the chip. The applications of the chip have reached into education, transportation, manufacturing and entertainment.
The worldwide electronics market has grown from $29 billion to nearly $957 billion since 1961. Projections point out that in the 21st century it will become the world’s single largest industry. This expansion will rely on the continued development of newer and better technologies — like those being developed around the world, e.g. wireless communication/internet connection, and DNA decoding.
(Sound Chip - IC)
In the future, there will be more new amazing encounter with electronic equipment with continuing advances in semiconductors. Perhaps in the next few years, you can call your overseas friend and seeing his/her smiling face in the screen on your cell phone. Your mother can turn on the oven from her car phone as she leaves her office at the end of the day. When you get home, dinner will be nearly done. Even better, it may be able to set your car on autopilot, then, you are free to look over notes for your next day’s meeting on your commute home. In USA, plans are being made for you to order a movie from the web, and within a matter of seconds, it is ready to view on your television at home. It sounds like science fiction, but new breakthroughs are only a short stride away, or already ready to be implemented.
However, there are several problems that can hinder the steady progress of IC; one of them is the speed of electrons that will ultimately set the limit on how fast information can travel. The power consumption, which leads to heat generation, is another. If you have too many transistors pack into a tiny area, and you can remove the heat generated by them. They would soon fail because of overheating (it means you can no longer control the electrons). Another problem to consider is that presently we base our physics in the classical regime but as the size of the IC gets smaller, then, it would come a time when quantum mechanics which governs the property of physical world in small dimension, will become important. This would mean a complete re-estimate of the IC is needed.
[About the author: Dr. Kok Wai CHEAH received his B.Sc. honor degree, M.Sc. degree, DIC and Ph.D. degree from Imperial College of London University. He is now an Associate Professor in the Department of Physics at Hong Kong Baptist University. His research interests include Nano-dimension Semiconductors, Organic and Inorganic Luminescence Materials, and Wide Band-gap Semiconductors.]
Semiconductor, Vacuum Tube, Transistor, Integrated Circuit (IC), radio receiver, rectifying properties, voltage potential, cat’s whisker diode, grid, vacuum tube, solid state equivalent of vacuum tube, oscilloscope screen, quantum mechanics, DNA decoding, speed of electrons, diode, capacitor, rectifiers, silicon wafer in planar technology, simple oscillator circuit
Related Topics in the syllabus:
Electrons, Circuits, power (heating effect when a current passes through a conductor)
Extensions (from the syllabus):
Bring out ideas: Nowadays, superconductor is a hit topic in electronic world. With the use of element of superconductors, electronic product, let say computers, can be more powerful. How can it make changes of the size, efficiency and affordable heat of the package of the electron circuits?
In the early development (first 50 years of the 20th century) of IC, what kind of electronic components were being used?
Suggest a main reason why vacuum tube is inconvenient to use.
Brittle, large size, not reliable, consumed more power and produced more heat.
Name two companies who are already involved in electronic industry in 1950s.
As IC becomes more and more complex and comprising hundreds or thousands of discrete components, why did Jack Kilby think that there is a need to integrate all the electronic components?
Components still had to be interconnected to constitute electronic circuits, and to hand-solder thousands of components to thousands of bits of wire were costly and time-consuming. It was unreliable too; soldered joint can fail and therefore every joint was a potential source of problem.
Points for further discussion:
What property of the semiconductor materials is useful in electronic application?
Give an example on the way of communication in the near future.
Do you agree the development of IC is important? Give your answer with reason(s).
Why electronic chips have changed the way we communicate?
The Nobel Prize is the first international award given annually since 1901 for those who had great contributions in physics, chemistry, medicine, literature and peace. Briefly describe
(a) Who founded the Nobel Prize;
(b) why the Nobel Prize is founded; and
(c) which organisation operates the Nobel Prize.
Jack S. Kilby was awarded one half of the first Nobel Prize of Physics (year 2000) in the new millennium for basic work on information and communication technology, specifically for his part in the invention of the integrated circuit. His achievements laid the foundations for the present information technology. What implication do you think that he was awarded the Nobel Prize of Physics at the beginning of the twenty-first century?
Prize Money is included for all awardees annually since 1901. However, the prize money for awardees in Physics was allocated to the Main Fund and Special Fund of Nobel Prize section in 1916, 1931, 1934 and 1940-42. what were the major reasons based on the global environment of the years?
Jack S. Kilby was shared half of the Nobel Prize of Physics (year 2000) in the new millennium. Who share the other half of the prize? What is the impact of his achievement on our life?
Who were the earliest Chinese winners of Nobel Prize in Physics? What years were they awarded the Nobel Prize in Physics? Which aspect in Physics they have contributed to lead the prize?
Even using IC in a circuit has a lot of advantages, there is no circuit just using IC as its electronic components. (If you have chance to look at the circuit of some electronic devices, you can find they have some resistors, capacitors or transistors in the circuit.) Why does not use IC to replace all these electronic components?
Imagine that if IC was not developed, what will the modern life be?
Now, most the use of vacuum tube diode is replaced by the use of IC. There, however, still have some electronic devices using vacuum tube diodes in their circuit. Find out which devices are still using vacuum tube diodes and why is IC used in the circuits.
Related Web Sites:
Integrated Circuit A quick tour on the history of Integrated Circuit (IC).
History of Innovation A tour of the history of Texas Instruments Incorporated.
Package structure This document shows the structure of typical IC packages.
Research in Analog Integrated Circuit Design This page is a summary of the research projects of a research group at the University of California at Berkeley.