Germanium transistor

The invention of the germanium transistor in 1947 [I, 2] marked the birth of modem microelectronics, a revolution that has profoundly influenced our current way of life. This early device was actually a bipolar transistor, a structure that is mainly used nowadays in amplifiers. However, logical circuits, and particularly microprocessors, preferentially use field-effect transistors (FETs), the concept of which was first proposed by Lilicnficld in 1930 [3], but was not used as a practical application until 1960 [4]. In a FET, the current flowing between two electrodes is controlled by the voltage applied to a third electrode. This operating mode recalls that of the vacuum triode, which was the building block of earlier radio and TV sets, and of the first electronic computers. 

The first solid-state transistor was made not from silicon but from the element below it in the Periodic Table germanium. This substance is also a semiconductor, and can be doped in the same way. William Shockley, Walter Brattain, and John Bardeen devised the germanium transistor at Bell Telephone Laboratories in New Jersey in 1947. It was a crude and clunky device (Fig. VJa) - bigger than a single one of today s silicon chips, which can house millions of miniaturized transistors, diodes, and other components (Fig. Vjb). The three inventors shared the Nobel Prize in physics in 1956. 

The control of charge flow by an electric quantity is a key issue of today s electronics. The concept to electrically specify the conductivity of a resistor by pure solid state effects was already proposed in 1928 by Julius Edgar Lilien-feld in Germany [1], The basic idea was to control the charge carrier density in a solid by an electric field, applied over a third electrode. However, there is no evidence for a practical realisation by Lilienfeld. The first report about a pure electrically controllable solid state device was the well know Germanium transistor from William Shockley, John Bardeen and Walter Brattain [2]. The new term transistor was later explained as a combination of the words transconductance and varistor . Meanwhile a broad variety of different transistor concepts exists, which, however, can be mainly subdivided in two basic operational principles ... 

Indium has many industrial uses for electronics and electrical applications [9] indium metal in germanium transistors indium alloys for soldering and glass sealing of electronic devices indium antimonide, arsenide, and phosphide in infrared detectors and semiconductor applications indium-silver alloys for brazing and electroplated indium metal for electrical connectors. For underground telephone cables, indium has been used to plate copper-to-aluminum connectors. About 2-5 tons of indium alloyed with silver and cadmium has been used annually in nuclear reactor control rods. 

Germanium is an important semiconductor material. The development of the germanium transistor opened the door to countless applications in solid-state electronics. Today silicon has taken over the role as the main transistor element but germanium is very much used in other advanced appHcations, such as for instance fiber optics and solar cells. 

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