Evolution of Transistors
X-ray image depicting the evolution of transistors. Left to right: 1951 Bell Labs original prototype of an A1698 germanium point-contact transistor—marketed later by Western Electric as the 2N22; 1953 Raytheon CK722—first mass-produced junction transistor; and a 2N6028 (4mm wide) silicon programmable unijunction transistor. Today, there can be billions of transistors in a fingernail-sized computer chip. Image taken with a ZEISS Xradia 620 Versa X-ray microscope.
—Herminso Villarraga-Gómez, Carl Zeiss Industrial Metrology, U.S.A.