ZnTe Compound Semiconductor Thin Films Electrodeposited from Acidic Aqueous Solution

摘要

Amorphous ZnTe compound semiconductor thin films can be electrodeposited from acidic aqueous solution containing citric acid. . Chemical composition of ZnTe thin films electrodeposited at -0.8 V is close to the stoichiometry composition and optimum cathode potential for electrodeposition of ZnTe is determined to ca. -0.8 V which is under potential range to the equilibrium potential of Zn. Film thickness of electrodeposited ZnTe is ca. 3 μm and the growth rate of ZnTe thin films is estimated to be ca. 3 nm?sec~(-1). Surface appearance of as-deposited ZnTe thin films looks black and that is composed of an amorphous phase. On the other hand, the thin films with annealing at 683 K turn reddish brown and that is composed of binary crystalline phases. Optical absorption is observed in the range less than ca. 550nm in the deposit with the binary phases of ZnTe and Te. Band gap energy of the deposits, which are annealed for 1 to 5 hours, is ca. 2.25 eV. Resistivity of as-deposited thin films is ca. 10~6 Ωm. On the other hand, that of the annealed thin films is ca. 10~(-1) Ωm which is smaller than the value of ZnTe single crystal.