Two-Band and Impurity-Band Conduction in the Cd3-xZnxAs2 Alloy Crystals

Galvanomagnetic properties of the Cd 3- x Zn x As 2 alloy crystals with x =1.2, 1.8 and 2.4 were measured and discussed in the temperature region from 1.8 to 370K. In the temperature dependence of the Hall coefficient a maximum was observed at a temperature, around which the resistivity varied approximately as exp ( e a / k T ), for n -Cd 1.8 Zn 1.2 As 2 containing ∼4×10 15 electrons/cm 3 and p -Cd 1.2 Zn 1.8 As 2 containing ∼3×10 16 holes/cm 3 . This fact suggests the presence of two bands with different carrier mobilities. In the latter case, one of the two may be an impurity band. Also, p -Cd 0.6 Zn 2.4 As 2 with an intermediate carrier density exhibited a positive magnetoresistance, Δ ρ/ρ∝ T -1 , at low temperatures, which was explained by means of the impurity conduction like that proposed for Ge, Si and other semiconductors.