Das elektrische Verhalten von AlSb
In previous papers the authors have reported on the semiconducting character of intermetallic compounds as CdSb. Here they describe similar experiments on AlSb which should be a semiconductor as saturated chemical compound. The present measurements confirm the semiconducting mechanism of AlSb also in the extrinsic range near room temperature, i.e. a decrease of resistivity with increasing temperature. The accuracy of these measurements and the purity of the AslSb-samples makes it possible to find below the intrinsic range two other activation energies of 0,53 and 0,08 eV, which were unknown hitherto. The positive sign of the thermoeletric force and of the rectifying curve prove that AlSb is a p-type conductor; perhaps the hole conduction is caused in analogy to CdSb by an impurity content of 0,01% Pb in the purest Sb-samples now available. Rectifying characteristics are measured for both low and high resistivity specimens, depending on different hole concentration. The authors could increase the barrier voltages from about 5 till 12 volts to more than 300 volts. The maximal rectifying ratio obtained is greater than 1:10^4. Specimens with high back voltages show small forward currents and vice versa. The metallurgical process and the corrosion of AlSb-samples observed but not overcome by Tammann and Rühenbeck are discussed in detail. The present authors observed precipitations of metallic Al on the grain boundaries and supposed that the corrosion by water vapor is starting from these Al-spots and is proceeding by an autocalalytic process. Infact, the corrosion velocity could be lowered by some orders of magnitude by avoiding or removing such precipitations of metallic Al.
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