Deep level transient spectroscopy of CdS/CdTe thin film solar cells

Abstract

Deep levels in polycrystalline n-CdS/p-CdTe photovoltaic structures have been studied by deep level transient spectroscopy ͑DLTS͒. The results were obtained from cells which have undergone different post-deposition treatment ͑as-deposited, heat treated, and heat treated in the presence of CdCl 2 ). The DLTS results showed a deep level distribution independent of the post-deposition treatment. For all samples the spectra were dominated by a hole trap, localized at E V ϩ0.48 eV. Metastable hole and electron traps were also observed, mainly in the heat treated ͑with and without a CdCl 2 layer͒ devices.

Heterojunction properties of electrodeposited CdTe/CdS solar cells

“…A literature summary of main trapping levels in CdTe/CdS cells is reported recently. 23 This work shows that both of the traps in our sample have been detected previously by deep level transient spectroscopy as electron traps. The E 2 trap that appears to be more common to detect 23 can be assigned to the interface states.…”

Admittance spectroscopy characterize graphite paste for back contact of CdTe thin film solar cells

“…This trap level with its σ t ~1.1×10 −13 cm 2 , was detected respectively in CdTe thin-film solar cells after treatment with CdCl 2 using DLTS measurements by Lourenço and Versluys [19,20]. In addition, Fiederle verified trap Cd i 2+ with value E v +0.51(±0.01) eV in crystal CdTe thin-film [21].…”

“…Three defect energy levels have been verified from the AS data, as summarized in [17,18]. The energy value was also founded in semiconductor CdTe thin-film [16,17], and CdTe thin-film solar cells undergone different post-deposition thermal treatment through DLTS by Lourenço [19], with its σ t close to 6.9×10 −16 cm 2 .…”

Process Development and Basic Studies of Electrochemically Deposited CdTe-Based Solar Cells; Annual Technical Report, Phase II, 16 May 1999-13 May 2000

“…After stressing of a cell this level shifts into the band gap by 0.22eV [17]. The H1 level of energy about Ev+0.35 eV was previously reported for the ED-grown, CSS-grown CdTe devices [11,12,18,20,21] and p-CdTe single crystals [10,12,22]. Usually it is attributed to Cu Cd substitution defects.…”