Tuning structural, electrical, linear, and nonlinear optical properties of cadmium zinc telluride quantum dot thin films

Quantum dots of Cd0.18Zn0.14Te0.68 thin films of various thicknesses are deposited on a glass substrate using inert gas condensation and characterized using many techniques. Structural analysis confirms the cubic polymorph of the thin films. The particle size increased from 5.7 to 10.35 nm as the film thickness increased from 10 to 100 nm. Bandgap calculations show two direct allowed transitions, one of which is 1.8 eV for different thicknesses. The other transition changes from the ultra-violet region (3.7 eV) for 10 nm thickness to yellow (2 eV) for 100 nm thickness, depending on the particle size. This result suggests that this material is suitable for use in multiple absorption layers of the same material rather than multilayers of different materials in tandem solar cells. The optical linear and nonlinear parameters highly depend on the particle size. Electrical conductivity shows intrinsic conduction with low activation energies from ambient temperature to 336 K.
 Graphical abstract