Characteristics of HfO2 and SiO2 on p-type silicon wafers using terahertz spectroscopy

H. Altan, A. Sengupta, D. Pham, H. Grebel, J. F. Federici

Research output: Contribution to journalArticlepeer-review


The effect of high-κ dielectric HfO2 films on 200 mm diameter p-type silicon substrates was investigated and compared with conventional dielectric material, SiO2. We employed all-optical characterization methods using terahertz (THz) time-domain spectroscopy and visible cw pump/THz probe spectroscopy. Measurements were performed on two sets of samples, each set containing both HfO2 and SiO2 coated wafers with varying thickness of oxide layer. One set had a protective coating of either photoresist or Si3N4 deposition above the oxide layer which in turn was on a heavily doped p+ layer on p-type silicon. The samples exhibited similar linear transmission in the THz frequency range studied. However, when using an Ar+-ion laser as an optical pump source, differential measurements (with and without the pump source) showed that the transmission was far smaller for the high-κ dielectric HfO2 films than its conventional dielectric SiO2 counterparts, indicating the presence of large photo-generated carrier density in the p-type substrate.

Original languageEnglish (US)
Article number001
Pages (from-to)457-463
Number of pages7
JournalSemiconductor Science and Technology
Issue number5
StatePublished - May 1 2007

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Materials Chemistry
  • Electrical and Electronic Engineering


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