Structural, optical, and electrical properties of vacuum evaporated Cu-doped ZnTe polycrystalline thin films
- Colorado School of Mines, Golden, CO (United States)
We have studied the structural, optical, and electrical properties of thermally evaporated, Cu-doped, ZnTe thin films as a function of Cu concentration and post-deposition annealing temperature. X-ray diffraction measurements showed that the ZnTe films evaporated on room temperature substrates were characterized by an average grain size of 300A with a (111) preferred orientation. Optical absorption measurements yielded a bandgap of 2.21 eV for undoped ZnTe. A bandgap shrinkage was observed for the Cu-doped films. The dark resistivity of the as-deposited ZnTe decreased by more than three orders of magnitude as the Cu concentration was increased from 4 to 8 at.% and decreased to less than 1 ohm-cm after annealing at 260{degree}C. For films doped with 6-7 at.% Cu, an increase of resistivity was also observed during annealing at 150-200{degree}C. The activation energy of the dark conductivity was measured as a function of Cu concentration and annealing temperature. Hall measurements yielded hole mobility values in the range between 0.1 and 1 cm{sup 2}/V.s for both as-deposited and annealed films. Solar cells with a CdS/CdTe/ZnTe/ metal structure were fabricated using Cu-doped ZnTe as a back contact layer on electrodeposited CdTe. Fill factors approaching 0. 75 and energy conversion efficiencies as high as 12.1% were obtained. 21 refs., 10 figs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 420849
- Journal Information:
- Journal of Electronic Materials, Journal Name: Journal of Electronic Materials Journal Issue: 9 Vol. 25; ISSN JECMA5; ISSN 0361-5235
- Country of Publication:
- United States
- Language:
- English
Similar Records
Study of ZnTe:Cu back contacts on CdTe/CdS thin film solar cells
Properties of ZnTe:Cu thin films and CdS/CdTe/ZnTe solar cells