Friday, June 21, 2013

The carbon Silicon saga –II

Like I mentioned yesterday, Silicon nearly missed in becoming the backbone of today’s digital world. That place was nearly snatched by Germanium, and we may be all talking of Germanium valley, California or Bangalore would be the Germanium valley of India.
William Shockley, an electrical engineer and physicist at Bell labs was trying to build a small silicon amplifier to replace vacuum tubes in mainframe computers. Vacuum tubes were fragile, prone to overheating and consumed a lot of space. These tubes performed two major functions in an electric circuit. One, it amplified electronic signals, so faint signals did not die and secondly they acted like a one way valve for electricity, so electrons could not flow backwards into circuit. Shockley knew that he could achieve the same with semiconducting materials. Shockley worked with Silicon and built a silicon amplifier, which did not amplify anything. After two unsuccessful years, he dumped the project to two underlings, John Bardeen and Walter Brattain. Bardeen and Brattain realised that silicon was too difficult to purify and instead substituted Germanium and built the world’s first solid-state amplifier in December 1947. It was named the transistor. Shockley, who was in Paris at this time, did not want to miss on the credits for the invention and he rushed back for all the photo-op’s. Today all the publicity photos at Bell Labs show Shockley standing in the centre and Bardeen and Brattain flanking him on either side. Shockley then pushed Bardeen to another lab, so that Shockley could develop a second generation, commercial friendly transistor and keep all the credit to himself. Bardeen was so disgusted that he resigned from Bell labs, took an academic post and gave up semiconductor research altogether. Soon germanium transistors were all around, from improving computing power to making pocket radios. But many scientists were still working on Silicon. Silicon was not only abundant; germanium transistors generated a lot of heat and stalled at high temperatures.
In 1954, at a semiconductor meet, after a speech about the unfeasibility of silicon transistors, an engineer from Texas got up and announced that he had with him a working silicon transistor. His name was Gordon Teal, he hooked up a Germanium run record player to speakers and lowered the players circuit in a pan of boiling oil. As expected the player stopped. He then replaced the Germanium transistor with a Silicon one and repeated the experiment and this time the music continued playing.
Silicon Transistors were back.
In 1958, Texas Instruments hired a Six foot six inch tall engineer called Jack Kilby. His job was to solve a computer hardware problem facing the industry. Though cheap silicon transistors were now available, newer computers required lots of them in their circuits. In addition to this, there also were carbon resistors and porcelain capacitors to deal with. All these components had to be hand soldered by technicians peering over a microscope. It was very common for the frail wires of the circuit to break and render the whole thing useless. Kilby was hired to solve this problem. Kilby managed to carve all the resistors, transistors and capacitors in once block of a semiconductor and the Integrated Circuit (IC) was born. Not trusting the purity of silicon, Kilby used Germanium for his IC. Soon IC’s allowed engineers to automate the carving process and make microscopic transistors- the first real computer chips. Kilby though never got full credit, one of Shockley’s proteges filed a rival and slightly more detailed patent claim a few months later and wrested the rights away from Kilby’s company. Silicon, it turned out was much cheaper than Germanium and plentiful in supply. Soon Kilby’s Germanium IC ended up in the Smithsonian museum and silicon IC’s were in the market. As Sam Kean neatly summarises in the book ‘The Disappearing spoon:’  “After germanium did all the work silicon became an icon and Germanium was banished to periodic table obscurity”
This post is inspired from the above mentioned book. The complete title “The Disappearing spoon: And other true tales of Madness, love and the history of the world from the periodic table of elements” quite a mouthful but a wonderful read.

No comments:

Post a Comment