The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

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A comprehensive review of zno materials and devices

Transparent conductors as solar energy materials: A panoramic review

A method for the synthesis of nearly monodisperse CuInS2 semiconductor nanocrystals (from <2 to 20 nm) was developed using generic and air-stable chemicals in a non-coordinating solvent. Such “greener” approaches also allowed the reaction temperatures to be below 200 °C. By introducing reactivity-controlling ligands for Cu, namely thiols, control of the Cu:In stoichiometric ratio in the nanocrystals was achieved. Amines were identified as catalytic reagents for the rapid oxidation of the CuInS2 nanocrystals, which could be prevented by the formation of CuInS2/ZnS core/shell nanocrystals by a one-pot approach. CuInS2/ZnS core/shell nanocrystals also showed greatly improved optical properties, with photoluminescence quantum yield up to about 30% and an emission peak position tunable from 500 to 950 nm. The versatility of the synthetic strategy was demonstrated by extending it to the synthesis of AgInS2 nanocrystals by simply replacing the copper salt by a silver salt.

Formation of high-quality I-III-VI semiconductor nanocrystals by tuning relative reactivity of cationic precursors.

Present status of transparent conducting oxide thin-film development for Indium-Tin-Oxide (ITO) substitutes

Transparent conducting oxides for electrode applications in light emitting and absorbing devices

Time-resolved photoluminescence in Cu(In,Ga)Se2 thin films and solar cells

Undoped and Ga-doped (3 wt %) n-type ZnO thin films were grown by a reactive plasma deposition method on glass substrates at 200 °C under an oxygen flow rate from 0 to 50 SCCM. In this paper, we report on the defect and band edge related signals in the optical absorption spectra for ZnO thin film by using a piezoelectric photothermal (PPT) spectroscopy, which is effective in observing a nonradiative transition process. The PPT peak around 2.5 eV was observed only for the undoped ZnO samples grown under a low oxygen flow rate. This signal is considered to be related to the oxygen vacancies, because it disappears with the increase of the oxygen flow rates. No corresponding peak was found for the Ga-doped samples. This result indicates that Ga doping inhibits the generation of the oxygen vacancies, and it agrees with that from the first-principle electronic band structure calculations. We have also carried out the theoretical calculation for the optical absorption edge of degenerated ZnO as a function of the...

Defect centers and optical absorption edge of degenerated semiconductor ZnO thin films grown by a reactive plasma deposition by means of piezoelectric photothermal spectroscopy

Effects of CdS buffer layers on photoluminescence properties of Cu(In,Ga)Se2 solar cells

Temperature-dependent photoluminescence measurements were carried out between 8 and 300 K on CuInS2 single crystals grown by a traveling heater method. Ten distinct peaks were present in the near-band edge region. Four unknown peaks, observed at 8 K, were found to be due to bound exciton emission. Moreover, the luminescence remained stable up to room temperature.

Sho Shirakata

Papers

Time-resolved photoluminescence in Cu(In,Ga)Se2 thin films and solar cells

Defect centers and optical absorption edge of degenerated semiconductor ZnO thin films grown by a reactive plasma deposition by means of piezoelectric photothermal spectroscopy

Effects of CdS buffer layers on photoluminescence properties of Cu(In,Ga)Se2 solar cells

Sharp band edge photoluminescence of high-purity CuInS2 single crystals

Dependence of carrier concentrations on oxygen pressure for Ga-doped ZnO prepared by ion plating method