One-step synthesis of PbSe-ZnSe composite thin film

This study investigates the preparation of PbSe-ZnSe composite thin films by simultaneous hot-wall deposition (HWD) from multiple resources. The XRD result reveals that the solubility limit of Pb in ZnSe is quite narrow, less than 1 mol%, with obvious phase-separation in the composite thin films. A nanoscale elemental mapping of the film containing 5 mol% PbSe indicates that isolated PbSe nanocrystals are dispersed in the ZnSe matrix. The optical absorption edge of the composite thin films shifts toward the low-photon-energy region as the PbSe content increases. The use of a phase-separating PbSe-ZnSe system and HWD techniques enables simple production of the composite package

Effect of iodine incorporation on characteristic properties of cadmium telluride deposited in aqueous solution

The electrodeposition of polycrystalline I-doped CdTe was successfully performed from aqueous solutions containing cadmium nitrate (Cd(NO3)2 and tellurium oxide (TeO2). The effects of different I-doping concentrations in the electrolytic bath on the deposited CdTe layers deposited were evaluated structurally, optically, morphologically and electronically using X-ray diffraction (XRD), ultraviolet-visible spectrophotometry, scanning electron microscopy, photoelectrochemical cell measurement and direct-current (DC) conductivity test respectively. The XRD show reduction in the (111) cubic CdTe peak intensity and the calculated crystallite size of the CdTe:I layers above 5 ppm I-doping. At I-doping of 1000 ppm of the CdTe-bath and above, the deposition of only crystalline Te due to the formation of Cd-I complexes debarring the deposition of Cd and co-deposition of CdTe in aqueous solution was observed. Morphologically, reductions in grain size were observed above 5 ppm I-doping with high pinhole density and the formation of cracks within the CdTe:I layers. For the as-deposited CdTe:I layers, conduction type remained n-type across all the explored I-doping concentration of 200 ppm. For the CdCl2 and Ga2(SO4)2+CdCl2 treated CdTe:I layers, the transition from n- to p-type conductivity was observed for the CdTe:I baths doped with 20 ppm and above due to the reduced cadmium deposition on the substrate. The highest conductivity was observed at 5 ppm I-doping of the CdTe-bath. Observations made on the CdTe:I in aqueous solution differs from the non-aqueous solvent documented in the literature. These results are reported systematically in this communication

Electrodeposition of CdTe thin films using nitrate precursor for applications in solar cells

Cadmium telluride (CdTe) thin films have been electrodeposited (ED) on glass/fluorine-doped tin oxide (FTO) substrates using simplified two-electrode system in acidic and aqueous solution containing Cd(NO3)2 4H2O and TeO2. The X-ray diffraction (XRD), optical absorption, photoelectrochemical (PEC) cell measurements, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been carried out to study the structural, optical, electrical and morphological properties of the CdTe layers. The XRD study shows that the ED-CdTe layers are polycrystalline with cubic crystal structure. Results obtained from optical absorption reveal that the bandgaps of the as-deposited and the CdCl2 treated CdTe layers are in the ranges ~1.50 to ~1.54 eV and ~1.46 to ~1.51 eV, respectively. Observation from PEC measurements indicates a p-, i- and n-type electrical conductivity for as-deposited CdTe layers grown in the cathodic voltage range (1,247–1,258) mV. The SEM images indicate noticeable change in CdTe grain size from ~85 to ~430 nm after CdCl2 treatment with uniform surface coverage of the glass/FTO substrate. The TEM images show the columnar growth structure for as-deposited and CdCl2 treated CdTe layers. The TEM images also indicate an increase in grain’s diameter from ~50 to ~200 nm after CdCl2 treatment