A Thumbnail History of Electronics

 

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VII. Electrons and Waves
The revolution in physics which was introduced by the emergence of the quantum theory of matter led to the invention of the devices of modern electronics. The roots of the quantum theory lie in unanswered questions of 19th Century Physics, which were resolved in 1927 by the Schrödinger theory which encompassed the wave/particle duality of radiation and matter discovered by Planck and DeBroglie. The quantum theory provided the foundation for the theories of conduction in metals and semiconductors which form the basis for solid state electronics. The physicists who created this scientific revolution were, for the most part, Europeans whose lives and work were disrupted in the 1930’s as many became refugees from Hitler.

boltz.gif (8446 bytes)Ludwig Eduard Boltzmann (1844 - 1906) was born and educated in Vienna, and held positions at Vienna, Graz, Munich and Leipzig. Boltzmann’s work in statistical mechanics used the concepts of probability to determine physical properties and contributed to the development of quantum mechanics. His work was met with hostility by many scientists: depressed and ill, Boltzmann committed suicide.

 

Max Karl Ernst Ludwig Planck (1858-1947), was one of the leaders of science in Germanyplanck.gif (7685 bytes) until his retirement in 1928. In 1900 he "guessed" the correct form for the blackbody radiation function and attempted to justify the formula by assuming that radiation consists of quanta of energy. Using the formula, Planck was able to deduce the value of h, the Boltzmann constant k, Avogadro’s number and the charge of the electron; he received the Nobel Prize in 1918. Plank, whose career was marked by its devotion to the highest ideals, died broken by a series of personal tragedies: his elder son was killed in World War I, his daughters both died in childbirth in the next decade, and his second son was implicated in the plot against Hitler and executed horribly by the Gestapo in 1945.

 

broglie2.gif (12327 bytes)(Prince) Louis-Victor de Broglie (1892-1987) and his elder brother, members of the French nobility, broke with family tradition and became physicists. His interest in conceptual problems in physics led to a doctoral thesis which evoked the astonishment and skepticism of the examining committee. He proposed that electrons had wave properties; this duality of matter and waves offered an explanation of the restricted motion of electrons around atomic nuclei. A copy of his thesis reached Einstein, whose enthusiastic response led in turn to Schrödinger’s invention of wave mechanics.

 

Erwin Schrödinger (1887-1961) was an Austrian Catholic who left Germany in 1933 in response to Nazi policies. After the Nazi takeover, he and his wife then fled Austria with a single suitcase to take refuge schroed.gif (9787 bytes)first in the Vatican and, later, in Ireland. Schrödinger’s theory replaced the definite atomic particles of classical theory with an equation for a wave function which is related to the probability of physical events. Oddly, Schrödinger was unhappy with his own invention and spent great effort in formulating objections to his theory. Schrödinger was a widely talented individual who not only wrote popularizations of science, but also contributed works on genetic structure, ancient Greek philosophy, and the history and philosophy of science.

 

fermi.gif (8971 bytes)Enrico Fermi (1901-1954), was the son of an Italian railroad employee. He received his doctorate from the University of Pisa at age 21. In 1926 he developed the statistical method which predicts the behavior of electrons and, shortly thereafter, was made a full professor at the University of Rome at age 26. In 1938, he left Italy with his family to receive the Nobel Prize and did not return; his known distaste for the Fascist regime and the fact that his wife was Jewish had led to vicious attacks in the rightist press. Fermi emigrated to the United States where, as part of the Manhattan Project at the University of Chicago, he led the team that achieved the first self-sustaining nuclear chain reaction

 

dirac2.gif (7839 bytes)P.A.M. Dirac (1902-1984) received a degree in Electrical Engineering from the University of Bristol, England, but failing to find work, went on to graduate study in Physics. He became one of the founders of quantum mechanics, predicted the existence of the positron, developed the theory of the spinning electron and introduced the quantum theory of radiation. He was awarded the Nobel Prize in 1933.

 

 

bloch.gif (2614 bytes)Felix Bloch (1905-1983) was at the University of Leipzig in 1928 when his doctoral thesis provided the theory of electrons in lattices which is the basis for the quantum theory of electrical conduction. Bloch was a Swiss Jew who left Germany and emigrated to the United States when Hitler came to power. He worked on the Manhattan Project during World War II. In 1952 he was awarded the Nobel Prize for his work on nuclear magnetic resonance. Bloch has been called "the Father of Solid-State Physics".  In the Bloch theory, electrons exist as waves in the solid lattice.  Interference between the waves and the lattice results in the exclusion of certain energy bands for the electrons in the solid.

 

peierls.gif (3539 bytes)(Sir) Rudolph Peierls (1907-1995), the son of a Jewish businessman, was born and educated in Germany but sought a post in Britain after Hitler came to power. He became a naturalized citizen and a professor of Physics, first at Birmingham and later at Oxford. In 1929 Peierls conceived the theory of positive carriers, electron defects or "holes", to explain the thermal and electrical conductivities of semiconductors and their negative Hall coefficients. In 1940, Peierls and Frisch alerted the British government of the possibility of producing an atomic bomb. There was some initial security difficulties, created, oddly, because of Peierls’ German background, but Peierls was eventually sent to work at Los Alamos.

 

(Sir) Alan Herries Wilson (1906-1976) was a British physicist on a fellowship in the same Zurich laboratory as Bloch when, in 1930, he recognized the difference between conductors and insulators; conductors have only partially-filled upper energy bands so that electrons in this band can acquire kinetic energy; the upper energy band is filled in an insulator.  In a semiconductor, the presence of impurities contribute electrons to the empty upper energy band.
 
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