THERMAL CONDUCTIVITY OF GERMANIUM STRONGLY ALLOYED WITH ARSENIC AND GALLIUM,
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
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A study was made of the effect of alloying germanium with donor and acceptor impurities in a wide range of concentrations with an aim at ascertaining the influence of the degree of doping. The impurity concentrations ranged from 1.4 x 10 to the 14th power to 10 to the 20th powercu cm and the tests were made in the temperature range 100-500K. The samples were single crystals grown by the Czochralski method under conditions ensuring homogeneity of the samples, and cut in the form of parallelepipeds measuring 4 x 5 x 12 mm. The thermal conductivity was measured by a stationary method in a vacuum of the order of 0.001 mm Hg. Tests at 300K have shown that, up to 10 to the 17th powercu cm, the thermal conductivity of germanium depends neither on the amount or the type of the doping impurity, exhibiting a plateau at a value 0.60 Wcm-deg. A higher concentrations, the thermal conductivity drops to 0.471 Wcm-deg for an arsenic content 5.45 x 10 to the 19th powercu cm, and to 0.53 Wcm-deg for germanium containing 1 x 10 to the 20th powercu cm of gallium. The temperature dependence of the strongly doped germanium is linear, whereas in the case of weak doping the growth of thermal resistance begins to exhibit a decrease. In purer samples k approximately T to the minus 0.23 power at T 300K and k approximately T to the minus 1.15 power 300K. The fact that the thermal conductivity is proportional to the reciprocal of the temperature offers evidence of the dominating role of three-phonon processes. Deviations from this proportionality is attributed to the appearance of photon thermal conductivity.
- Metallurgy and Metallography
- Solid State Physics