Thermodynamics of Cathodic ZnTe Electrodeposition Using Basic Ammoniacal Electrolytes: Why CdTe Can Deposit While ZnTe Cannot

Potentiostatic cathodic electrodeposition of ZnTe compound was attempted using ammoniacal basic electrolytes in which Zn(II) and Te(IV) species were dissolved to form Zn(NH3)(4)(2+) and TeO32- ions. The ZnTe electrodeposition ended unsuccessfully although CdTe can electrodeposit from similar ammoniacal solutions under a variety of conditions. The solubility of Te(IV) species and cathodic polarization behaviors indicated the absence of interionic interaction between Zn(II) and Te(IV) ions unlike the case between Cd(II) and Te(IV). A potential-pH diagram of the Zn-Te-NH3-H2O system constructed based on diagrams of the Zn-NH3-H2O and Te-H2O systems also demonstrated several thermodynamic and/or kinetic factors that make ZnTe deposition more difficult than those of CdTe.