Spray pyrolysis of aqueous solutions that include copper(II) acetate, glucose, and 2-propanol was studied for the formation of cuprous oxide (Cu 2 O) thin films on glass substrates. The deposition conditions, based on the phase relations of the films, were investigated in terms of solution concentration and substrate temperature. Also, the formation process was kinetically discussed. The Cu 2 O thin film obtained here was composed of rounded grains ∼50 nm in size with a surface roughness of ∼30 nm. This film was reddish yellow and showed indirect and direct bandgap energies of 1.95 and 2.60 eV, respectively. Furthermore, the film exhibited p-type conduction, with a resistivity of ∼100 ⍀ؒcm.

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The cathodic reaction of chlorine residual (CR) combined with anodic pre-electrolysis enables the quantification of CR as a gaseous chlorine. Potential-step chronocoulometry was successfully applied to extend the CR detection range.

We have investigated pretreatment conditions of GaP substrates for molecular beam epitaxy of ZnS-based materials. Oxide removal of GaP substrates was carried out with or without irradiation of P or/and Zn molecular beams under S-free environment. The effects of the beam irradiation and the growth temperature on the initial growth mode and crystalline quality of ZnS epitaxial layers were studied. It was shown that the ZnS epitaxial layers grown on the P-and Zn-irradiated substrates at the growth temperatures of 350-450 C show quasi-two-dimensional nucleation and good crystalline quality.Introduction ZnS is one of possible materials for short-wavelength optoelectronic devices [1], because of its large bandgap (3.7 eV at root temperature) and availability of alloys such as ZnCdS [2] and ZnMgS [3] that can construct heterostructures. In fact, we have previously reported successful growth of ZnS-based ZnS/ZnMgS [4] and ZnCdS/ ZnMgS [5] quantum wells. However, the crystalline quality of ZnS-based epitaxial layers is not high enough as compared to ZnSe-based materials. This might be one of the reasons for the difficulty in obtaining low resistive p-type ZnS. To improve the crystalline quality, lattice matching to substrates seems to be essential. For this purpose, GaP is suitable because it has small lattice-mismatch (0.77%) to ZnS. For a ZnSe/GaAs system which is a similar quasi-lattice-matching system, the effect of the substrate surface condition on the properties of the epitaxial layer has been extensively studied [6]. In contrast, the pretreatment conditions of the GaP substrate for epitaxial growth of ZnS-based materials has not yet been well established. Presumably for this reason, there have been only a few reports on the lattice-matching effect of ZnS-based epitaxial layers on GaP substrates [7,8].In this paper, we report the effect of pretreatment conditions of the GaP substrate on the properties of ZnS layers grown by molecular beam epitaxy (MBE). The effect of the growth temperature is also studied.