It is well known that preparing temperatures and defects are highly related to deep-level impurities. In our studies, the CdTe polycrystalline films have been prepared at various temperatures by close spaced sublimati...It is well known that preparing temperatures and defects are highly related to deep-level impurities. In our studies, the CdTe polycrystalline films have been prepared at various temperatures by close spaced sublimation （CSS）. The different preparing temperature effects on CdS/CdTe solar cells and deep-level impurities have been investigated by I-V and C-V measurements and deep level transient spectroscopy （DLTS）. By comparison, less dark saturated current density, higher carrier concentration, and better photovoltaic performance are demonstrated in a 580℃sample. Also there is less deep-level impurity recombination, because the lower hole trap concentration is present in this sample. In addition, three deep levels, Ev ＋ 0.341 eV（H4）, E, ＋ 0.226 eV（HS） and Ec - 0.147 eV（E3）, are found in the 580℃sample, and the possible source of deep levels is analysed and discussed.展开更多
Deep levels in Cds/CdTe thin film solar cells have a potent influence on the electrical property of these devices. As an essential layer in the solar cell device structure, back contact is believed to induce some deep...Deep levels in Cds/CdTe thin film solar cells have a potent influence on the electrical property of these devices. As an essential layer in the solar cell device structure, back contact is believed to induce some deep defects in the CdTe thin film. With the help of deep level transient spectroscopy （DLTS）, we study the deep levels in CdS/CdTe thin film solar cells with Te：Cu back contact. One hole trap and one electron trap are observed. The hole trap H1, localized at Ev＋0.128~eV, originates from the vacancy of Cd （VCd. The electron trap E1, found at Ec-0.178~eV, is considered to be correlated with the interstitial Cui= in CdTe.展开更多
The deep-level defects of Cd Zn Te（CZT）crystals grown by the modified vertical Bridgman（MVB）method act as trapping centers or recombination centers in the band gap,which have significant effects on its electrical ...The deep-level defects of Cd Zn Te（CZT）crystals grown by the modified vertical Bridgman（MVB）method act as trapping centers or recombination centers in the band gap,which have significant effects on its electrical properties.The resistivity and electron mobility–lifetime product of high resistivity Cd（0.9）Zn（0.1）Te wafer marked CZT1 and low resistivity Cd（0.9）Zn（0.1）Te wafer marked CZT2 were tested respectively.Their deep-level defects were identified by thermally stimulated current（TSC）spectroscopy and thermoelectric effect spectroscopy（TEES）respectively.Then the trap-related parameters were characterized by the simultaneous multiple peak analysis（SIMPA）method.The deep donor level（EDD/dominating dark current was calculated by the relationship between dark current and temperature.The Fermi-level was characterized by current–voltage measurements of temperature dependence.The width of the band gap was characterized by ultraviolet-visible-infrared transmittance spectroscopy.The results show the traps concentration and capture cross section of CZT1 are lower than CZT2,so its electron mobility–lifetime product is greater than CZT2.The Fermi-level of CZT1 is closer to the middle gap than CZT2.The degree of Fermi-level pinned by EDDof CZT1 is larger than CZT2.It can be concluded that the resistivity of CZT crystals increases as the degree of Fermi-level pinned near the middle gap by the deep donor level enlarges.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 60506004)the National High Technology Research and Development Program of China (Grant No. 2003AA513010)
文摘It is well known that preparing temperatures and defects are highly related to deep-level impurities. In our studies, the CdTe polycrystalline films have been prepared at various temperatures by close spaced sublimation （CSS）. The different preparing temperature effects on CdS/CdTe solar cells and deep-level impurities have been investigated by I-V and C-V measurements and deep level transient spectroscopy （DLTS）. By comparison, less dark saturated current density, higher carrier concentration, and better photovoltaic performance are demonstrated in a 580℃sample. Also there is less deep-level impurity recombination, because the lower hole trap concentration is present in this sample. In addition, three deep levels, Ev ＋ 0.341 eV（H4）, E, ＋ 0.226 eV（HS） and Ec - 0.147 eV（E3）, are found in the 580℃sample, and the possible source of deep levels is analysed and discussed.
基金supported by the National Natural Science Foundation of China (Grant No. 60506004)the National High Technology Research and Development Program of China (Grant No. 2003AA513010)
文摘Deep levels in Cds/CdTe thin film solar cells have a potent influence on the electrical property of these devices. As an essential layer in the solar cell device structure, back contact is believed to induce some deep defects in the CdTe thin film. With the help of deep level transient spectroscopy （DLTS）, we study the deep levels in CdS/CdTe thin film solar cells with Te：Cu back contact. One hole trap and one electron trap are observed. The hole trap H1, localized at Ev＋0.128~eV, originates from the vacancy of Cd （VCd. The electron trap E1, found at Ec-0.178~eV, is considered to be correlated with the interstitial Cui= in CdTe.
基金supported by the National Natural Science Foundation of China(No.51502234)the Scientific Research Plan Projects of Shaanxi Provincial Department of Education of China(No.15JS040)
文摘The deep-level defects of Cd Zn Te（CZT）crystals grown by the modified vertical Bridgman（MVB）method act as trapping centers or recombination centers in the band gap,which have significant effects on its electrical properties.The resistivity and electron mobility–lifetime product of high resistivity Cd（0.9）Zn（0.1）Te wafer marked CZT1 and low resistivity Cd（0.9）Zn（0.1）Te wafer marked CZT2 were tested respectively.Their deep-level defects were identified by thermally stimulated current（TSC）spectroscopy and thermoelectric effect spectroscopy（TEES）respectively.Then the trap-related parameters were characterized by the simultaneous multiple peak analysis（SIMPA）method.The deep donor level（EDD/dominating dark current was calculated by the relationship between dark current and temperature.The Fermi-level was characterized by current–voltage measurements of temperature dependence.The width of the band gap was characterized by ultraviolet-visible-infrared transmittance spectroscopy.The results show the traps concentration and capture cross section of CZT1 are lower than CZT2,so its electron mobility–lifetime product is greater than CZT2.The Fermi-level of CZT1 is closer to the middle gap than CZT2.The degree of Fermi-level pinned by EDDof CZT1 is larger than CZT2.It can be concluded that the resistivity of CZT crystals increases as the degree of Fermi-level pinned near the middle gap by the deep donor level enlarges.
