Absorption and photoconductivity properties of ZnTe thin films formed by pulsed-laser deposition on glass

Pulsed-laser deposition (PLD) of ZnTe was performed at λpld = 1064 nm and λpld = 532 nm employing nanosecond pulses of a Nd:YAG laser. Thin ZnTe films (thickness ≈2 μm) were deposited at room temperature on fused silica glass substrates. X-ray diffraction revealed the influence of the ablation wavelengths on the deposited film texture. The film formed at λpld = 532 nm is amorphous, whereas the one ablated at λpld = 1064 nm was amorphous but contained zincblende and wurtzite crystallites as well. The samples exhibited a broad photocurrent response extending into the visible and infrared part of the spectrum to almost 1 eV. The absorption coefficients, which were measured with standard constant photocurrent method (s-CPM), showed that the bandgap of the films is considerably shifted to lower energies of 1.0 eV as compared to the crystalline source material of 2.26 eV.