In your December 2012 issue, in the story "Transistors Pick Up Speed With GaAs" on page 50, I noticed a major error. Being an antique semiconductor engineer, I must let you know that almost all transistor were made with germaniumsome with germanium as a dopantfrom Dr. Shockley's time up until Fairchild developed the planar process so that silicon could be used on a production basis. Millions of germanium devices were made by over a dozen manufacturers until the silicon planar process made obsolete the alloy junction germanium types. Then, when Mr. Kilby figured out how to make an integrated circuit on silicon at Texas Instruments, the semiconductor world changed. Most of the rest of the story was generally correct and interesting. Keep up the good work.

Paul Grace