Influence of substrates porosity on the optical behavior of Zn3P2 nanorod thin films

•Zn3P2 nanostructural films prepared by thermal evaporation under high vacuum.•Study the effect of kind of substrates on the structural and optical properties.•Determination of all the optical results.•Free carrier concentration/effective mass.

Zn3P2 nanostructural films were prepared by inert gas condensation technique with constant argon gas flow rate of 3 × 10−1 Torr, 300 K substrate temperature and film thickness of 50 nm. The films were deposited on different porosity glass substrates. The porosity of substrates carried out by etching with dilute HF acid, was detected through the average pore size estimated from SEM image. The X-ray diffraction (XRD) patterns showed that the deposited films have nanocrystalline tetragonal structure with broad lines (400) and (303). The Transmission Electron Microscope (TEM) micro graphs showed that, these investigated films deposited on untreated glass substrates have nanorod particles with length of ∼41.2 nm and ∼5.4 nm width. The porosity of the used substrate affects strongly the optical behavior of the Zn3P2 nanorod films. The optical transmission and reflection of Zn3P2 thin films deposited on substrates with different time of etching were measured and showed highest absorption spectra for films of highest substrate porosity. The optical energy gap decreased with increasing porosity of substrates. The porosity of substrates affects the oscillating energy, dispersion energy and oscillator strength. The ratio of free carrier concentration/effective mass (N/m∗) were determined for all investigated samples.