Cu 2 ZnSnS 4 (CZTS) thin films were deposited on glass substrates by using spin-coating and an annealing process, which can improve the crystallinity and morphology of the thin films. The grain size, optical gap, and atomic contents of copper (Cu), zinc (Zn), tin (Sn), and sulfur (S) in a CZTS thin film absorber relate to the concentrations of aqueous precursor solutions containing copper chloride (CuCl 2 ), zinc chloride (ZnCl 2 ), tin chloride (SnCl 2 ), and thiourea (SC(NH 2 ) 2 ), whereas the electrical properties of CZTS thin films depend on the annealing temperature and the atomic content ratios of Cu/(Zn + Sn) and Zn/Sn. All of the CZTS films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS), Raman spectroscopy, and Hall measurements. Furthermore, CZTS thin film was deposited on an n-type silicon substrate by using spin-coating to form an Mo/p-CZTS/n-Si/Al heterostructured solar cell. The p-CZTS/n-Si heterostructured solar cell showed a conversion efficiency of 1.13% with V oc = 520 mV, J sc = 3.28 mA/cm 2 , and fill-factor (FF) = 66%.

Direct bonding of gallium arsenide on silicon is studied. The technology is expected to enable the easy integration of gallium arsenide optoelectronic devices with silicon very-large-scale integrated circuits. The interface quality of n-GaAs/p-Si can be improved with a thermal annealing process. It is examined by the current-voltage characteristics of the n-GaAs/p-Si diode. The bonding strength was found to be sufficiently high and could “high enough to” withstand the subsequent grinding and polishing procedures of the bonded wafers.

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A high-quality nitrogen-doped p-type ZnSe epilayer on (100) GaAs substrate was obtained under selenium-rich growth conditions by low-pressure organometallic chemical vapor deposition. Ammonia was used as the dopant source. The resistivity (0.5 Ω cm) and the free-carrier concentration (p=8.8×1017 cm−3) of as-grown ZnSe:N were derived from Hall measurements. With selenium-rich growth conditions, we can reduce the concentration of compensation defects (VSe-Zn-NSe which acts as a donor in ZnSe). Nitrogen is found to incorporate in ZnSe as a shallow level, which is examined by the dependence of free-to-acceptor emission on the NH3/H2Se molar ratio. The carrier concentration of as-grown ZnSe:N seems to change insignificantly within a wide range of growth temperatures. That is thought to be useful for device fabrication due to uniformity considerations.