True Genius The Life and Science of John Bardeen: The Only Winner of Two Nobel Prizes in Physics (2002) / Chapter Skim
Currently Skimming:
8 The Transistor
8 The Transistor
Pages 115-141
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 115... ...
Summit offered excellent schools, parks, and convenient transportation; it was a stop on the Hudson Tubes, the subway to New York City. From Summit one could easily catch a bus to Murray Hill, where Bell Laboratories had built its new research campus.
|
From page 116... ...
"Baths are infrequent and water must be heated on the electric stove for dishwashing and cleaning." Bill Shockley dropped by to help, but mainly distracted them with his storytelling. At first it was difficult to eat meals at home, for the family had no refrigerator.
|
From page 117... ...
On warm summer days the children could swim and enjoy frozen treats at the local pool. The family enjoyed walking along the trails of the Watchung Mountain Reservation, half a block from Primrose Place.
|
From page 118... ...
In their home, the decorations included "a scale and a scythe and a few things like that from western living." About a year after Bardeen came to Bell Labs, Conyers Herring arrived there with his bride, Louise Preusch, a Barnard College graduate with a mathematics major and physics minor. Herring was assigned to the Physical Electronics Division of the Physical Research Department.
|
From page 119... ...
Just before a visit to Bell Labs by the distinguished British physicist Nevill Mott, lean asked Bill to please shave off his beard. When he refused, "she grew two big pigtails for the event and tied pink bows on the ends." When Bill expressed displeasure with the pigtails and bows, lean said, " 'I'll get rid of them if you get rid of your beard,' which he did." John and lane saw the Shockleys less often as lane grew less tolerant of Bill's boastful displays.
|
From page 120... ...
Pulling up to the entrance of the Murray Hill facility on Mountain Avenue was the daily ritual by which he shifted between his two spheres. In the first decades after its incorporation on January 1, 1925, the Bell Telephone Laboratories had occupied an elegant, twelve-story brick and sandstone building at 463 West Street in lower Manhattan.
|
From page 121... ...
The idea to move the laboratory into a cleaner and larger space reemerged when the Second World War brought new funds and a much larger staff to Bell Labs. In 1941 the massive structure in Murray Hill known as "Building 1 " was hastily completed in time to house the wartime exodus from the cramped West Street building.
|
From page 122... ...
Electrically, this metal-semiconductor interface played the same role in an electronic circuit as a vacuum tube diode, but it could function at higher frequencies. The research also dealt with "forming" the metal whiskers, producing pure semiconductor crystals, adding impurities ("doping")
|
From page 123... ...
Also included in the collection were papers on silicon by Fred Seitz at DuPont or at the University of Pennsylvania. The next time John saw Fred, he said, "Now I know what you did during the war." The essential difference between a triode and a diode vacuum tube is the single crucial element known as the "grid" (see Figure 81~.
|
From page 124... ...
For these reasons and others (including the cost, bulkiness, and fragility of glass tubes) , Bell Labs looked to semiconductors to replace vacuum tube diodes and triodes.
|
From page 125... ...
into a triode. Arranging two wires so they barely contacted the green oxide on either side of a rusty porch screen and adjusting the voltage applied, Shockley expected the jagged screen to function like the grid of a vacuum tube.
|
From page 126... ...
An electric field was applied perpendicular to a thin slab of silicon; the field drew charges in the slab to its surface. In a thin sample, Shockley argued, the field would cause a substantial change in the available charge carriers.
|
From page 127... ...
Unable to contribute to the conduction, the trapped electrons substantially decreased the change in conductivity caused by the applied field. That was why Shockley's field effect design failed.
|
From page 128... ...
During the remainder of 1946 and throughout 1947, Shockley's engagement with the field effect studies flagged, for he developed new interests during the summer of 1947, when he and Bardeen took an extended tour of European laboratories. It was to be the last time Bardeen and Shockley would share an extended collegial exchange.
|
From page 129... ...
Brian Pippard, was also present. At Shoenberg's suggestion Pippard had studied Heinz London's prewar experiments on the penetration depth of magnetic fields in superconductors.
|
From page 130... ...
. The London theory, with its radical assumption of the long-range ordering between electrons, had predicted the size of the penetration depth of magnetic fields.
|
From page 131... ...
" He immersed the system in various liquids including distilled water and was "completely flabbergasted" to find that the photovoltaic effect he was studying increased whenever the liquid was an electrolyte. Soon Brattain was demonstrating these things "to anybody in the group that would listen." Bardeen suggested that the mobile ions in the electrolytes might be creating a large enough electric field to overcome the surface states.
|
From page 132... ...
Bardeen loved to peer over Brattain's shoulder and watch him prepare his experiments. Sometimes Bardeen would offer Brattain a hand in routine tasks, such as recording measurements or holding a piece of apparatus in place while Brattain soldered it.
|
From page 133... ...
Thus by using an inversion layer contiguous with the bulk material, instead of a thin film deposited on its surface, one could perhaps get around not only the difficulty of depositing a very thin layer of semiconductor, but also that of the low mobility of charge in thin films. For the contact, Bardeen proposed using a sharp tungsten point.
|
From page 134... ...
"Iohn Bardeen was great at coming up with approximate guesses of this kind and making the right guess," Brattain recalled. Brattain happened to have a piece of the special germanium in his laboratory, so he and Bardeen tried the experiment that very afternoon.
|
From page 135... ...
They decided to dispense with the electrolyte and instead take advantage of an effect that Brattain happened to notice earlier that day. When he had applied a steady electric field to the glycol borate, the electrolyte had etched the surface of the germanium and caused a green oxide film (similar to rust)
|
From page 136... ...
Output current Control voltage ~J 1 Evaporated gold | Oxide layer \.* P-type inversion layer N-type germanium Tunnsten point 1 FIGURE 8-4 Bardeen's and Brattain's field effect model of December 11, 1947.
|
From page 137... ...
, in common use today. Bardeen would later joke that his and Brattain's invention of the point-contact transistor slowed the quest for the field effect transistor for several years.
|
From page 138... ...
"The observed effect" was not very large and no real power amplification was seen. Bardeen suggested "that if we really were introducing carriers into the surface and wanted to get a real large interaction, you have to get the electrodes extremely close together, within a thousandth of an inch or so." He therefore proposed a geometry (shown in Figure 8-5)
|
From page 139... ...
The wire and gold spot would be replaced by two metallic line contacts set down on the germanium with a separation between them of only a few thousandths of a centimeter. (At this stage they believed that line contacts would give a stronger effect than point contacts.
|
From page 140... ...
They gathered nervously for the demonstration, held in one of the executive offices at Murray Hill. Brattain had arranged the apparatus so that some observers could speak over the input circuit while others could hear the output signal over earphones, or see it displayed on the screen of an oscilloscope.
|
From page 141... ...
Thus A acts as a cathode and B as a plate in the analogous vacuum tube circuit. The ground corresponds to the grid, so the action is similar to that of a grounded grid tube.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.