Metastable Ge nanocrystalline in SiGe matrix for photodiode

Yao Tsung Ouyang, Chien Hao Su, Jenq Yang Chang, Shao Liang Cheng, Po Chen Lin, Albert T. Wu

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Amorphous Si 1-x Ge x films were prepared by co-sputtering on an oxidized Si wafer, followed by rapid thermal annealing to form nanocrystal films. The formation of Ge nanocrystals was not at thermodynamic equilibrium formed in the amorphous Si 1-x Ge x matrix. High-resolution transmission electron microscopy was used to characterize the increase in the size of the grains in the Ge nanocrystals as the Ge content increased. The Ge nanocrystals have a greater absorption in the near-infrared region and higher carrier mobility than SiGe crystals, and the variation in their grain sizes can be used to tune the bandgap. This characteristic was exploited herein to fabricate n-Si 1-x Ge x /p-Si 1-x Ge x p-n diodes on insulating substrates, which were then examined by analyzing their current-voltage characteristics. The rectifying property became stronger as the fraction of Ge in the Si 1-x Ge x films increased. The Si 1-x Ge x diodes are utilized as photodetectors that have a large output current under illumination. This paper elucidates the correlations between the structural, optical and electrical properties and the p-n junction performance of the film.

Original languageEnglish
Pages (from-to)387-392
Number of pages6
JournalApplied Surface Science
StatePublished - 15 Sep 2015


  • High-resolution transmission electron microscopy
  • Metastable SiGe
  • Nanocrystalline Ge
  • Rapid thermal annealing


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