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Point Contact Transistors: More to the Point

In What’s the point?: The Point Contact transistor I discussed Shockley’s white paper on the theory of the Point Contact Transistor. Let’s look further into this early transistor design.

It is interesting to note that the first point contact transistor was created from the semiconductor germanium. Paper clips and razor blades were used to make the first transistor prototype1 .

So in 1947, John Bardeen and Walter Brattain, put together a few of these transistors and connected them with some other components to make an audio amplifier. They showed their audio amplifier to some chief executives at Bell Telephone Company. The executives were impressed because this device did not need time to “warm up” like the heaters in vacuum tube circuits. They saw the power of this new technology.

The Nobel Prize organization commented: This invention was the spark that ignited a huge research effort in solid state electronics. Bardeen and Brattain received the Nobel Prize in Physics, 1956, together with William Shockley, “for their researches on semiconductors and their discovery of the transistor effect.” Shockley had developed a so-called junction transistor, which was built on thin slices of different types of semiconductor material pressed together. The junction transistor was easier to understand theoretically, and could be manufactured more reliably.

In the image below, Shockley mentions Deathnium , a name given by early electronic engineers to a trap in semiconductors that reduced the lifetime of both electron and hole charge carriers.

In this image, Schockley showed a way in which the Deathnium recombination process can occur. He says that there is an imperfection of some sort in the crystal which is capable of trapping an electron. (Image courtesy of Reference 1)

In this image, Schockley showed a way in which the Deathnium recombination process can occur. He says that there is an imperfection of some sort in the crystal which is capable of trapping an electron. (Image courtesy of Reference 1)

In part (a) of the figure, Shockley shows the electron approaching this ‘imperfection’. Shockley goes on to describe the event1 :

Part (b) shows what happens after the electron is trapped. If a hole reaches the center while the electron -is trapped in it, the electron may easily jump into the hole. The center is then left in its original condition and is ready to recombine another electron-hole pair. Evidently, the reverse process can also go on and the center can generate hole-electron pairs by proceeding through the steps represented by (c), (d), and (e) in the figure. In (d) the deathnium center is supposed to have captured an electron, not an excess electron in this case but one from an electron-pair bond. As a result, a hole is created which diffuses away from the center. Subsequently, in (e) the electron jumps out of the deathnium center which is then returned to its original state and may create other electron-hole pairs or recombine them as the case may be. Conservation of energy is achieved in these processes by the simultaneous absorption or generation of photons and phonons.

My good friend, Arlie Stonestreet II, Chief Engineer with Ultra-ICE, sent me these following X-Ray images he captured of a point contact transistor he has in his collection. You can even see the port-hole where they would manually twiddle the point contact wires.

Check out some of the photos that Kirkwood Rough (He is a long-time Analog Engineer-extraordinaire, presently at Upstairs Amps. See his patents here) shared with Arlie from his collection. Most interesting are the transistor curves. Arlie tried to duplicate that on his transistor but couldn't get good readings….

Semiconductor amplification regarding the transistor action, with voltage, current and power gain, was experimentally observed by Bardeen and Brattain in n-type polycrystalline Germanium on December 16, 1947. This was the result of the strategically placed of gold-plated line contacts in nearby single crystal grains of the polycrystalline material.

Shive’s experiment at Bell Labs in 19482 showed the importance of the geometrical configuration in determining the extent of bulk transport. Shockley’s contribution of injection over a barrier, p-n junction theory and junction transistor theory outlined the mathematical description of Bardeen and Brattain’s previously disclosed transistor action by using a one-dimensional analysis.

The rest is history. More to come on this subject on Planet Analog in the future. We need to understand and never lose sight of our rich history of electronics in order to understand who we are and how we got here today, just as a family needs to know its ancestry history for their identity.

References

1 Transistor Electronics: Imperfections, Unipolar and Analog Transistors, W. SHOCKLEY, PROCEEDINGS OF THE I.R.E., 1952

2 More Things in Heaven and Earth: A Celebration of Physics at the Millennium

11 comments on “Point Contact Transistors: More to the Point

  1. Hooey0
    May 10, 2017

    Steve – Very interesting and informative post, as always.

    It brought back memories of my early days learning about transistors. When I was in college, it was all about tubes, and semiconductors were in their infancy. 

    I still have some CK722 PNP junction transistors that were packaged in a blue case. I wonder if they still function.

    Keep up the great work!

  2. Norberto
    May 11, 2017

    More more interesting discovery

    • Ghostbuster
      September 24, 2020

      Hi Norberto my name is Ghostbuster of Stratford and I live in Stratford Ontario Canada and I saw the Mothman I am just wondering why is the Mothman in Stratford Ontario Canada and so far away from point pleasant and the Mothman I saw had very big red glowing eyes and a wing span of at least 20 feet

  3. paul.justus
    May 12, 2017

    Thanks for this article!

  4. Ghostbuster
    September 24, 2020

    Hi I am a Ghostbuster in Stratford Ontario Canada and I just saw the Mothman and the Mothman just picked me up off of my top porch and I was able to hurt the Mothman does anyone know why the Mothman is in Stratford Ontario Canada and why would the Mothman attack me I am a Ghostbuster and I have seen everything from Ghosts to Demons to Vampires to werewolves to shadow people and I have never ever seen the Mothman until tonight all I saw was the big red glowing eyes a human body with wingspan about 20 ft does anyone know why it’s so far away from port present and why is the Mothman in Stratford Ontario Canada

  5. Ghostbuster
    September 24, 2020

    Why is the Mothman so far away from point present and why is the Mothman in Stratford Ontario Canada

  6. Ghostbuster
    September 24, 2020

    Why is the Mothman in Stratford Ontario Canada and so far away from point pleasant

  7. Ghostbuster
    September 25, 2020

    Can anyone tell me why the Mothman is in Stratford Ontario Canada and why the Mothman is so far away from point pleasant

  8. Ghostbuster
    September 25, 2020

    Does anyone know how to kill the Mothman garlic doesn’t work silver that don’t work my ghostbusting equipment don’t work I got to go to sunlight right maybe a wooden steak through the heart anyone got any ideas and why didn’t anyone tell me this creature is immune to Silver and garlic and if you did what do you have told me

  9. Ghostbuster
    September 25, 2020

    Does anyone know how to kill the Mothman garlic doesn’t work silver that don’t work my ghostbusting equipment don’t work I got to go to sunlight right maybe a wooden steak through the heart anyone got any ideas and why didn’t anyone tell me this creature is immune to Silver and garlic and if you did would you have told me

  10. Ghostbuster
    September 27, 2020

    This Tuesday I will be selling my soul to the devil to become a full pure blood vampire cuz I’m only half human half vampire there’s a creature called Mothman I can’t kill it cuz I’m half human half vampire the only thing I can kill the mothman is a bite from a pureblood vampire so on Tuesday this Tuesday coming up I’m going to be selling my soul to the devil become a full pure blood vampire I already have a daylight ring my daylight ring protects me as a half human Half Vampire so I do not burn in the Sun but the only way to kill them off man is a bite from a pure blood vampire I have no choice garlic doesn’t work silver that don’t work my ghostbusting equipment doesn’t work my superpowers doesn’t work my Mutant Powers don’t work I had mutants help me try and kill the Mothman I even got my friends from Sky-high school to help me try to kill the Mothman I even contact professor Xavier and I had all of the mutants from there helping me out I even have friends that are called the mutants underground which hides from Sentinel services and Sentinel services are people who take Mutants like myself and then Sentinel services kills the Mutants and I can’t do anything about it so I got in contact my Indian tribe from Seattle to help me kill the Mothman nothing is working so the only thing that can kill the Mothman is a bite from a pure blood vampire but since I’m only half human half vampire it is not going to work so in that case I have to sell my soul to the devil and I’m going to become a full pure blood vampire and I’m going to kill the Mothman this Tuesday night in the Stratford Avondale cemetery aka the Stratford graveyard and since I am selling my soul to the devil to become a full pure blood Vampire I will be able to finally kill the Mothman

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