Cadmium oxide crystals are prepared by reacting cadmium vapor with oxygen at temperatures of 870°K_??_970°K. Their growth is in the forms of needles, plates, cubes, swords and twined dendrites. Measurements of the electric conductivity and the Hall effect made on needle-like crystals at temperatures between 4°K and 600°K show that the specimens are fully degenerated
n-type semiconductors and possess the free electrons of the order of 10
18cm
-3 in concentration and of about 500cm
2volt
-1sec
-1 in Hall mobility. The free electrons are probably originated from nonstoichiometric excess of Cd atoms which are situated at interstitial positions. From the change in electric conductivity with annealing temperature, the formation energy of interstitial Cd atoms is estimated at 0.53eV. The activation energy of mobility of interstitial atoms is estimated at 1.67eV from diffusion constant. The dependence of the conductivity on the partial pressure of oxygen at 920°K is expressed in terms of the relation σ_??_
P02 -1/6.0. This shows that one excess Cd atom produces just two free electrons.
抄録全体を表示