Preparation of Zn(In)Se films from alloyed precursors

Single-phase cubic Zn(In)Se thin film growth by Se vapor selenization of Zn(In) alloy precursors films is described. Depositing the Zn(In) precursor film at higher substrate temperatures changes the In/Zn composition and also yields highly crystalline Zn(In)Se films. The In/Zn ratio in the selenized film is higher in comparison to that of the precursor due to differential selenization kinetics and the complex In–Se and Zn–Se reaction chemistry. The resistivity of the Zn(In)Se film depends on the In/Zn ratio. Initially, the resistivity increases with increased indium incorporation due to increased defect concentration and then decreases at higher In/Zn ratios because of lower grain-boundary effects and reduced trap density owing to improvement in film crystallinity. Treatment with vapor-phase Zn compensates for Zn vacancies in the film, reduces electrically inactive defects, and increases doping efficiency, thereby lowering the resistivities to ∼1 Ω cm. Hot-probe and thermoelectric power measurements show that all low resistive ZnSe films are n-type.