Electrical characterization of vacuum-deposited n-CdS/p-CdTe heterojunction devices

Bayhan H., Ercelebi C.

SEMICONDUCTOR SCIENCE AND TECHNOLOGY, vol.12, no.5, pp.600-608, 1997 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 12 Issue: 5
  • Publication Date: 1997
  • Doi Number: 10.1088/0268-1242/12/5/014
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.600-608
  • Middle East Technical University Affiliated: No


The effects of post-deposition processes such as CdCl2 dip and/or annealing in air on the material and device properties of vacuum-evaporated Au-CdTe/CdS-TO heterojunction solar cells have been investigated. The CdCl2 dip followed by air annealing at 300 degrees C for 5 min improved the device efficiency significantly, resulting in decreased CdTe resistivity and enhanced grain size. The temperature-dependent current-voltage analysis indicated that above 280 K interface recombination dominates the current transport mechanism for the as-grown samples, while depletion region recombination starts to be dominant after annealing the samples with CdCl2. Below 280 K multistep tunnelling is identified to be the dominant transport mechanism. Frequency-dependent capacitance-voltage studies revealed that after annealing with CdCl2 the density of interface states decreases and the quality of the heterointerface improves. The capacitance of the CdS/CdTe heterojunctions has been analysed using a model based on the existence of a single dominant trap level, identified at 0.40 eV above the valence band with a concentration of 5.1 x 10(15) Cm-3.