The Physics
Factbook
An encyclopedia of scientific essays

Resistivity of Germanium

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Bibliographic Entry Result
(w/surrounding text)
Standardized
Result
Cutnell, John D. & Johnson, Kenneth W. Physics Fourth Edition. Canada: John Wiley & Sons, Inc., 1998.
materialResistivity ρ(Ω·m)
germanium0.5 ^b
0.5 Ω·m
Sherwood, Richard. Germanium (Ge)- Germanium. School of Systems Engineering, 19 January 2004. "Absorption of n-type single crystal material was originally found by Capron and Brill in 1973, to be superior to that of p-type germanium from ninety-two samples investigated with resistivities ranging from 0.9 Ωcm to 57Ωcm" 0.009–0.57 Ω·m
Cichanoswki, Tommy. Semiconductors Materials, Junctions, and Devices.1967. "Semiconductors materials lie in the range between these two extremes, as shown in Fig. 1. Pure germanium has a resistivity of 60 ohm-centimeters." 0.60 Ω·m
Nave, Carl. Resistivity & Temperature Coefficient at 20°C. HyperPhysics. 2003.
MaterialResistivity ρ (ohm m)Temperature coefficient per degree C
Germanium*1-500x10^-5-.05
*the resistivity of semiconductors depends strongly on the presence of impurities
in the material, a fact which makes them useful in solid state materials.
0.001–0.5 Ω·m

Germanium is a semiconductor. It is a rare element and is never found in a pure form. The invention of "doping" popularized germanium. By adding small amounts of other substances, it lowered germanium's resistivity and increased its ability to conduct electricity. Doped germanium is used in infrared spectroscopes, camera lenses, electric guitar amplifiers and other devices.

There are two types of "doping", n-type doping and p-type doping. In the n-type doping, atoms that have one more valence electron than the semiconductor atom are added to the semiconductor. This extra electron, which cannot form an electron pair bond, becomes an excess electron. This decreases the semiconductor's resistivity. In p-type doping, atoms with one less valence electron than the semiconductor atom are added to the semiconductor. This will result in "incomplete" bonds or holes in the structure. This will encourage the flow of electrons in the semiconductor material and lower its resistivity.

Semiconductors are essential to the operation of computers, calculators, radios, television sets, video games and many other devices. A semiconductor has electrical properties between metals and insulators but similar to all materials, its resistivity will decrease and will conduct more electricity as its temperature is increased. Resistivity is a material's opposition to the flow of electric current and is the reciprocal of conductivity. It is measured in ohm-meters (Ω·m). The formula is ρ = RA/L, where R is resistance, A is the cross-sectional area and L is the length of the conductor.

Stanley Ko -- 2004