Tuning light absorption by band gap engineering in ZnCdO as a function of MOVPE-synthesis conditions and annealing

Options of flow rate and growth temperature variations were investigated in order to reveal limitations for single phase wurtzite ZnCdO synthesis by atmospheric pressure metal organic vapor phase epitaxy (MOVPE). It is found that in spite of efficient Cd incorporation (up to 60%), the wurtzite phase and the corresponding single step absorption threshold dominate only up to a Cd content ≤17% in the as-grown samples. Post-fabrication anneals reveal two characteristic optical absorption edges at ∼2.3 and ∼3.15 eV that were associated with direct band gaps of cubic CdO and thermodynamically stable wurtzite ZnCdO, respectively.