Monthly Archives: July 2021

Photo: Intel Corp.

I have in my notebooks from [1956] a complete description of the tunnel diode, the speaker told the audience at a symposium on innovation at the MIT Club of New York, in New York City, in December 1976. It was quite a revelation, because the speaker wasnt Leo Esaki, who had won the 1973 Nobel Prize in physics for inventing the tunnel diode in the late 1950s. It was Robert N. Noyce, cofounder of Intel Corp., Santa Clara, Calif.; inventor of the first practical integrated circuit; and a man who, as far as anyone knew before that speech, had no connection to the most storied electronic device never to be manufactured in large numbers.

Engineers coveted the tunnel diode for its extremely fast switching timestens of picosecondsat a time when transistors loped along at milliseconds. But it never found commercial success, though it was occasionally used as a very fast switch. As a two-terminal device, the diode could not readily be designed for amplification, unlike a three-terminal transistor, whose circuit applications were then growing astronomically. Nevertheless, the tunnel diode was a seminal invention. It provided the first physical evidence that the phenomenon of tunneling, a key postulate of quantum mechanics, was more than an intriguing theory.

Quantum mechanics, the foundation of modern physics, is an elaborate conceptual framework that predicts the behavior of matter and radiation at the atomic level. One of its most fundamental notions is that the exchange of energy at the subatomic level is constrained to certain levels, or quantitiesin a word, quantized.

Many of the core concepts and phenomena of quantum mechanics are almost completely counterintuitive. For example, consider a piece of semiconductor joined to an insulator. From the point of view of classical physics theory, the electrons in the semiconductor are like rubber balls, and the insulator is like a low garden wall. An electron would have no chance of getting over the barrier unless its energy were higher than the barriers. But according to quantum mechanics, the phenomenon of tunneling ensures that for certain conditions an electron with less energy than the barriers will not bounce off the wall but will instead tunnel right through it.

Ever since the late 1920s, physicists had debated about whether tunneling really occurred in solids. The tunnel diode offered the first compelling experimental evidence that it did.

When Esaki, then a 49-year-old semiconductor research scientist at IBM Corp., won his Nobel Prize in 1973, neither he nor the Nobel committee had any idea about Noyces work. Esaki had made a tunnel diode and measured its current versus voltage behavior 16 years earlier, when he was working at the company now called Sony Corp. in his native Japan. The Nobel committee, in fact, dated Esakis discovery from 1957, roughly contemporaneous with Noyces recollected work in the same field. Stig Lundqvist of the Swedish Royal Academy of Sciences used the electrons as balls against the wall analogy in his speech presenting the 1973 Nobel Prize in physics to Esaki; Ivar Giaever and Brian David Josephson shared the award for discovering different aspects of the tunneling phenomenon in solids.

In Good Company: The eight engineers and scientists, including Robert N. Noyce (right) and Gordon E. Moore (standing second from left), who cofounded Fairchild Semiconductor in 1957, are pictured here on the firms production floor in its earlyyears.Photo: Intel Corp.

Almost every important discovery since the start of the industrial age has a contested history. Heinrich Gobel, from a town near Hanover in Germany, filed suit in 1893 claiming that he, not Thomas Edison, had invented the light bulb years earlier in New York City. Something similar has occurred for the airplane, telephone, rotor encryption machine, television, integrated circuit, and microprocessor, to name but a few. Such counterclaims often have meritinvention and research are often group activities, and discoveries regularly appear in different places at almost precisely the same time. And sometimes such claims come from experimenting hacks eager for a measure of recognition for themselves.

Noyce was no hack, obviouslyhis integrated circuit nestles at the heart of essentially every piece of modern electronics. In fact, the invention of the IC was recognized as a Nobel-level achievement in 2000, when the prize for physics was awarded to Jack S. Kilby, credited by U.S. courts as the coinventor of the IC. Unfortunately for Noyce, he missed his chance to join the pantheon of laureates when he died in 1990; the prizes are not awarded posthumously.

Nor was Noyce pursuing glory when he mentioned his work in his talk at that symposium in 1976. In fact, immediately after claiming to have the invention in his notebooks, Noyce said, The work had been done elsewhere [by Leo Esaki] and was published shortly thereafter. He had mentioned it in the first place only because he thought the way his boss had handled Noyces tunnel diode efforts in 1956 may be instructive in how not to motivate people.

Noyces boss at that time was William B. Shockley, the brilliant, mercurial, ambitious, autocratic, and eccentric physicist. He was the sort of man who thought nothing of publicly subjecting his employees to lie-detector tests. As the young Noyce had his insight about the tunnel diode, Shockley himself was only weeks away from his own Nobel Prize in physics, awarded for his 1947 invention, along with two colleagues, John Bardeen and Walter Brattain, of the transistor.

Shockley had started Shockley Semiconductor Laboratory in 1955 with the self-proclaimed goal of making a million dollars and seeing his name in The Wall Street Journal. Noyce headed the transistor group at Shockley Lab. With a Ph.D. in physical electronics and two years in a transistor research lab at Philco Corp., he was the most experienced semiconductor researcher among Shockleys several dozen employees.

On 14 August 1956, Noyce noted an idea for a negative resistance diode in his lab notebook. With most diodes, current increases with increased voltagethe more voltage applied to the device, the more current passes through it.

In a diode, the current under a forward voltage, or bias, is relatively large, while little current results when the bias is reversed. For a semiconductor diode, such behavior is obtained by adding impurity atoms. Esakis semiconductor was germanium. He used two types of impurities. So-called donor atoms have more electrons in their outer orbits than do the outer orbits of germanium atoms. The excess electrons become free electrons, available for conduction. A semiconductor with an excess of electrons is called n-type.

Similarly, if the germanium is doped with impurity atoms that hold fewer electrons in their outer orbits than germanium, the impurity atoms will take away, or accept, electrons from the semiconductor atoms, leaving behind deficiencies of electrons, known as holes. A semiconductor with an excess of holes, each one considered to have a positive charge, is called a p-type semiconductor.

Germanium can be doped to create p- and n-type sections that butt against each other and form what is called a p-n junction. In a p-n junction, a potential difference normally builds up across a narrow region near where the p-type and n-type semiconductors come into contact. This built-in potential sets up a barrier against the passage of holes into the n-type material and the passage of electrons into the p-type. Applying an external bias across the diode changes the barriers height. A forward biasobtained by connecting a batterys positive terminal to the p side and its negative terminal to the n sidelowers the barrier, allowing electrons to flow easily from the n side to the p side. Reverse the polarity, and the height of the barrier rises, prohibiting the flow of electrons.

Noyce, however, made a startling prediction. First he proposed the existence of a semiconductor whose regions of opposite polarity were each doped with roughly a thousand times more impurities than was usual at the time. When a forward bias increasing from zero was applied to such a heavily doped diode (which Noyce called degenerate), he predicted that current would initially increase at a greater rate than for a normal diode. This phenomenon would occur because the high impurity density would, in effect, make it possible for the balls (electrons) to tunnel through the wall (the junctions potential barrier). At some point, increasing the voltage further would decrease the tunneling current, but at still higher voltages, the current would increase because of the nontunneling diode current.

Noyce discussed his ideas with his friend Gordon E. Moore, a chemist who had joined Shockley Lab a day before Noyce. He then brought his notebook to Shockley, fully expecting him to be impressed. Instead, the boss showed no interest in the idea, Noyce said. The lab was not equipped to do anything profitable with Noyces thoughts, and besides, Shockley was a fiercely competitive man who resented his employees pursuing ideas that he had not personally placed on their research agendas. Disappointed, Noyce closed his lab book and went on to other projects more in line with Shockleys wishes.

Until now, no one other than Moore and Shockley had seen Robert Noyces 1956 description of a tunnel diode. But Noyce copied his work and saved it. How he managed to copy these pages is unclearphotocopy technology was in its infancy in the late 1950s, and Noyce never made note of going back to his Shockley notebooks later in lifebut that the pages are legitimate is indisputable. Leslie Berlin, one of this articles authors, found them in January 2001 tucked in one of Noyces Fairchild notebooks stored in Santa Clara, Calif., at a company that prefers not to be identified.

Berlin compared these copied pages to the only surviving notebook from Shockley Lab: the book belonging to William Shockley housed in the Special Collections of Stanford University, in California. The pages on which Noyces ideas are written are clearly from the same type of lab book that Shockley issued to his staff, and the handwriting is undoubtedly Noyces. This, along with the date of Noyces work (which correlates with his 1976 comments about it), and Moores recollections of the event, further validate their authenticity.

A quick comparison of Noyces notebook pages with Esakis seminal paper, New Phenomenon in Narrow Germanium p-n Junctions, published in Physical Review in January 1958 (and received by that journal in October 1957), shows striking parallels. Both men used an energy-band diagram that represents the electron and hole energies on the y (vertical) axis versus their position in the p-n junction on the x (horizontal) axis [see sidebar, The Noyce Diode,two pages from Noyces notebook].

Noyces energy-level diagram, which is now called an energy-band diagram [on the left-hand page], shows where the electrons and holes are located. It also illustrates the conditions necessary for tunneling current. The upper solid line in the diagram represents the bottom of the semiconductors conduction band; in this band electrons can move freely as a result of the donor atoms. The lower solid line represents the top of the valence band, where acceptor impurities allow holes to move freely. The separation between the conduction and valence bands is the energy gap, or Eg , and is the range in energy where no electrons or holes are permitted. For this reason, Eg is sometimes called the forbidden gap.

In Noyces diagram, the Fermi energy, or Ef , represents the energy boundary for most of the holes in the p-type semiconductor and most of the free electrons in the n-type. For a highly doped, or degenerate, semiconductor, Ef falls below the edge of the valence band and rises above the edge of the conduction band. Electrons sink so they fill the lowest energy levels in the conduction band, while holes float and fill the highest levels of the valence band. Therefore, it is the holes between the top of the valence band and Ef and the free electrons between Ef and the bottom of the conduction band that are significant for tunneling.

The region between the p and the n sides where the valence and conduction band edges bend is called the depletion region; this is where the potential barrier exists. This region narrows for large donor and acceptor concentrations and would be less than 10 nanometers for a tunnel diode.

Note that without an applied bias, the holes on the p side are at a higher energy than the electrons on the n side. For tunneling to occur, there must be holes at the same energy as the free electrons. But a forward bias (a positive voltage connected to the p side), raises Ef and the conduction-band electrons on the n side with respect to Ef on the p side by the amount of the bias voltage. Now there are free electrons at the same energy as the holes, and the electrons can tunnel through the potential barrier to holes on the p side, resulting in a current. As the forward bias is increased, more free electrons and holes are at the same energy and the tunneling current increases.

Both Noyce and Esaki recognized that as the bias increased further, Ef on the n side would be raised further with respect to Ef on the p side and the concentration of free electrons at the same energy as holes would diminish and result in a reduced tunneling current, as shown in Noyces current (I) vs. voltage (V) plot. At a larger bias, the normal diode current would flow at the voltage Eg in Noyces plot.

This plot [on the right-hand page] is very similar to the measured I-V plot that Esaki shows. This phenomenon of decreasing current with increasing voltage is negative resistance, a characteristic that has been exploited to build oscillators.

But there was one important difference between Noyces and Esakis work. Noyce only predicted the drop in current (the evidence of tunneling) would occur. Esaki, who actually built a device to demonstrate his ideas, showed that it would. This difference is crucialmany good ideas die en route from the mind to the lab bench.

Noyces failure to implement his brilliant idea was almost certainly a direct result of Shockleys discouraging comments to him in 1956. Noyce was an experimentalist at heart. (He admired people who did things, his friend Maurice Newstein explained to one of the authors in 2003.) Noyce would later prove a bit of an iconoclast as well, joining a covert effort to build silicon transistors at Shockley whenever the boss, who had decided the lab should focus its attention on an obscure device he had invented called a four-layer diode, was away. But in August 1956, Noyce was 29 years old and not yet six months into his job at Shockley Lab. If his boss told him to drop an idea, at that point he would have done it.

Noyce no longer worked for Shockley when he read Leo Esakis Physical Review article in 1958. In September 1957, he, Moore, and six other Shockley employeesmore than half the senior technical staffhad left their temperamental boss to start their own transistor company, Fairchild Semiconductor. Shockleys business venture, meanwhile, withered (he joined the Stanford faculty in 1963), and he suffered the additional indignity of watching his proteges new company achieve phenomenal success. In less than a decade, Fairchildunder Noyces leadershipgrew to employ 11 000 people and generate more than US $12 million in profits.

The publication of Esakis article caused quite a sensation in the electronics community. At an international physics conference in 1958, the audience for Esakis presentation was overflowing. Interestingly, Esaki credits William Shockley, who explicitly mentioned Esakis work in his keynote address earlier to the conference, with the large attendance at his presentation.

We can never know why Shockley changed his mind about the importance of the diode, but there are several possible explanations. Shockley was infamous for his swings of opinionone person who worked for him said he was regularly jerking the company back and forth. Similar remarks from other colleagues indicate that Shockley may have changed his mind in this case. Moreover, the grudge he bore against the eight Fairchild founders was still fresh in 1958.

After reading Esakis article, Noyce brought his copy of Physical Review to Moore and laid it on his desk. Noyce could not mask the irritation he felt with William Shockley and, even more, with himself for not pursuing his ideas after Shockley dismissed them. If I had gone one step further, he told Moore, who would go on to found Intel with him in 1968, I would have doneit.

Leslie Berlin is a visiting scholar in the Program in the History and Philosophy of Science and Technology at Stanford University, in California. Her biography of Robert Noyce, The Man Behind the Microchip: Robert Noyce and the Invention of Silicon Valley, will be published by Oxford University Press on 1 June.

H. Craig Casey Jr. is Professor Emeritus at Duke University, in Durham, N.C. He is a life fellow of the IEEE and a past president of the Electron Devices Society.

Leo Esakis lecture Long Journey Into Tunneling, which he gave when awarded the Nobel Prize in physics in 1973, is available at http://nobelprize.org/physics/laureates/1973/esaki-lecture.html.

An interactive Web site that graphically illustrates the current mechanisms in a tunnel diode is at http://www.shef.ac.uk/eee/teach/resources/diode/tunnel.html.

For more on William Shockley, see Crystal Fire: The Birth of the Information Age, by Michael Riordan and Lillian Hoddeson (W.W. Norton, 1997).

Read the rest here:

Robert Noyce and the Tunnel Diode - IEEE Spectrum

The following is an adapted excerpt from the book The Extended Mind. It is reprinted with permission of the author.

If you'd like to make smarter choices and sounder decisions and who doesn't? you might want to take advantage of a resource you already have close at hand: your interoception. Interoception is, simply stated, an awareness of the inner state of the body. Just as we have sensors that take in information from the outside world (retinas, cochleas, taste buds, olfactory bulbs), we have sensors inside our bodies that send our brains a constant flow of data from within. These sensations are generated in places all over the body in our internal organs, in our muscles, even in our bones and then travel via multiple pathways to a structure in the brain called the insula. Such internal reports are merged with several other streams of information our active thoughts and memories, sensory inputs gathered from the external world and integrated into a single snapshot of our present condition, a sense of "how I feel" in the moment, as well as a sense of the actions we must take to maintain a state of internal balance.

To understand the role interoception can play in smart decision-making, it's important to know that the world is full of far more information than our conscious minds can process. However, we are also able to collect and store the volumes of information we encounter on a non-conscious basis. As we proceed through each day, we are continuously apprehending and storing regularities in our experience, tagging them for future reference. Through this information-gathering and pattern-identifying process, we come to know things but we're typically not able to articulate the content of such knowledge or to ascertain just how we came to know it. This trove of data remains mostly under the surface of consciousness, and that's usually a good thing. Its submerged status preserves our limited stores of attention and working memory for other uses.

A study led by cognitive scientist Pawel Lewicki demonstrates this process in microcosm. Participants in Lewicki's experiment were directed to watch a computer screen on which a cross-shaped target would appear, then disappear, then reappear in a new location; periodically they were asked to predict where the target would show up next. Over the course of several hours of exposure to the target's movements, the participants' predictions grew more and more accurate. They had figured out the pattern behind the target's peregrinations. But they could not put this knowledge into words, even when the experimenters offered them money to do so. The subjects were not able to describe "anything even close to the real nature" of the pattern, Lewicki observes. The movements of the target operated according to a pattern too complex for the conscious mind to accommodate but the capacious realm that lies below consciousness was more than roomy enough to contain it.

"Nonconscious information acquisition," as Lewicki calls it, along with the ensuing application of such information, is happening in our lives all the time. As we navigate a new situation, we're scrolling through our mental archive of stored patterns from the past, checking for ones that apply to our current circumstances. We're not aware that these searches are under way; as Lewicki observes, "The human cognitive system is not equipped to handle such tasks on the consciously controlled level." He adds, "Our conscious thinking needs to rely on notes and flowcharts and lists of 'if-then' statements or on computers to do the same job which our non-consciously operating processing algorithms can do without external help, and instantly."

But if our knowledge of these patterns is not conscious, how then can we make use of it? The answer is that, when a potentially relevant pattern is detected, it's our interoceptive faculty that tips us off: with a shiver or a sigh, a quickening of the breath or a tensing of the muscles. The body is rung like a bell to alert us to this useful and otherwise inaccessible information. Though we typically think of the brain as telling the body what to do, just as much does the body guide the brain with an array of subtle nudges and prods. (One psychologist has called this guide our "somatic rudder.") Researchers have even captured the body in mid-nudge, as it alerts its inhabitant to the appearance of a pattern that she may not have known she was looking for.

Such interoceptive prodding was visible during a gambling game that formed the basis of an experiment led by neuroscientist Antonio Damasio, a professor at the University of Southern California. In the game, presented on a computer screen, players were given a starting purse of two thousand "dollars" and were shown four decks of digital cards. Their task, they were told, was to turn the cards in the decks face-up, choosing which decks to draw from such that they would lose the least amount of money and win the most. As they started clicking to turn over cards, players began encountering rewards bonuses of $50 here, $100 there and also penalties, in which small or large amounts of money were taken away. What the experimenters had arranged, but the players were not told, was that decks A and B were "bad" they held lots of large penalties in store and decks C and D were "good," bestowing more rewards than penalties over time.

How Our Brains Feel Emotion | Antonio Damasio | Big Think http://www.youtube.com

As they played the game, the participants' state of physiological arousal was monitored via electrodes attached to their fingers; these electrodes kept track of their level of "skin conductance." When our nervous systems are stimulated by an awareness of potential threat, we start to perspire in a barely perceptible way. This slight sheen of sweat momentarily turns our skin into a better conductor of electricity. Researchers can thus use skin conductance as a measure of nervous system arousal. Looking over the data collected by the skin sensors, Damasio and his colleagues noticed something interesting: after the participants had been playing for a short while, their skin conductance began to spike when they contemplated clicking on the bad decks of cards. Even more striking, the players started avoiding the bad decks, gravitating increasingly to the good decks. As in the Lewicki study, subjects got better at the task over time, losing less and winning more.

Yet interviews with the participants showed that they had no awareness of why they had begun choosing some decks over others until late in the game, long after their skin conductance had started flaring. By card 10 (about forty-five seconds into the game), measures of skin conductance showed that their bodies were wise to the way the game was rigged. But even ten turns later on card 20 "all indicated that they did not have a clue about what was going on," the researchers noted. It took until card 50 was turned, and several minutes had elapsed, for all the participants to express a conscious hunch that decks A and B were riskier. Their bodies figured it out long before their brains did. Subsequent studies supplied an additional, and crucial, finding: players who were more interoceptively aware were more apt to make smart choices within the game. For them, the body's wise counsel came through loud and clear.

Damasio's fast-paced game shows us something important. The body not only grants us access to information that is more complex than what our conscious minds can accommodate. It also marshals this information at a pace that is far quicker than our conscious minds can handle. The benefits of the body's intervention extend well beyond winning a card game; the real world, after all, is full of dynamic and uncertain situations, in which there is no time to ponder all the pros and cons. When we rely on the conscious mind alone, we lose but when we listen to the body, we gain a winning edge.

Annie Murphy Paul is a science writer who covers research on learning and cognition. She is the author of The Extended Mind: The Power of Thinking Outside the Brain, from which this article is adapted.

Excerpt from:

Why information is central to physics and the universe itself - Big Think

The year is 1641. We open in France, where confusingly, everyone is speaking English. A Scottish man has been caught selling weapons to enemies of Louis XIII, and as punishment is forced to wear a red-hot iron mask forever. Cut to the not too distant future, where the mans descendant, Christopher Eccleston, is presenting a lecture about newly weaponised flying metal bugs to some Nato employees. Originally developed to isolate and kill cancer cells, at MARS industries we discovered how to program nanomites to do almost anything. For example eat metal. It turns out nanomites can also be injected into rocket warheads, and thus the back story and premise of GI Joe: The Rise of Cobra is explained in less than a minute.

The opening sets the tone for the film that follows speedy, irony-free B-movie action nonsense, delivered to you with the efficiency of a Big Mac on a Friday night And if it requires Christopher Eccleston to do a PowerPoint presentation so we can get on with watching helicopters blow up in slow motion, then dammit Christopher Eccleston will do a PowerPoint. On top of which, this particular Big Mac is filled with Channing Tatum.

Despite his previous acting highlights including the Step Up dance movies and grinding topless in the background of the video for Ricky Martins She Bangs, when asked about GI Joe in an interview in 2012, Channing Tatum said, I fucking hate that movie. Luckily for us, in 2009 Channing Tatum did a three-movie deal with Paramount and was forced to accept the GI Joe role to avoid being sued.

Despite his dislike of the film, Channing Tatum is still Channing Tatum and both he and his massive arms give it their all and he has gone to the Michael Bay School of Turning Around in Slow Motion While Holding a Machine Gun. After turning around slowly, he and his partner Marlon Wayans load some nanomite warheads into a jeep, refer to a group of muscular male soldiers as ladies and tell them to mount up. Strap in, everyone.

What follows is a plot of such madness and a cast of characters so enormous (IMDb lists 144 in total) its understandable that it required a PowerPoint to set it up. The truck is ambushed by Channing Tatums ex-girlfriend, Sienna Miller, and after a lengthy fight in which several members of elite army unit GI Joe parachute in to save the day, Tatum and Wayans are transported to an underground base in the Egyptian desert to participate in a training montage soundtracked by the UK band Bus Stops dance rap cover of T-Rexs Get It On. (Fun fact: Bus Stop were fronted by rapper and professional football manager Darren Daz Sampson, who went on to represent Britain in 2006s Eurovision Song Contest.) Channing Tatum wins a gladiatorial pugil stick fight with GI Joes resident masked ninja, Snake Eyes, and to celebrate the boys all take their tops off.

A semi-naked Marlon Wayans attempts to charm one of the Joes (they are collectively referred to as Joes) confusingly named Scarlett OHara, as she jogs on a treadmill while reading a book about quantum physics. (It is not clear why she needs to read a book about quantum physics when her job is beating people up dont worry about it.) Tatum puts on something called a Delta 6 accelerator suit and travels to Paris to stop Sienna Miller blowing up the Eiffel Tower, before charging around the Champs-lyses running after tanks, jumping through bus windows and flipping over Renault Mganes. Joseph Gordon Levitt appears to explain cobras to everyone using a CGI snake in a glass box (They are vicious). Chaos reigns.

Writer/director Stephen Sommers was also in charge of both The Mummy and the 90s B-movie classic Deep Rising, and although in comparison GI Joe contains a more noughties post-Transformers fixation on guns and machinery than those two films, there is a similar air of fun, unapologetic action campness throughout. If youre happy to suspend your disbelief to its very limits and relax into 1 hour and 58 minutes of revolving door cast, plot delivered via flashbacks and laughably hammy dialogue, plus Channing Tatum blowing things up in slow motion this is the film for you. And give me that kind of Big Mac silliness over po-faced serious blockbuster action, any day of the week.

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Hear me out: why GI Joe: The Rise of Cobra isnt a bad movie - The Guardian