Solid immersion lenses for enhancing the optical resolution of thermal and electroluminescence mapping of GaN-on-SiC transistors

James W Pomeroy*, Martin H H Kuball

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

7 Citations (Scopus)
341 Downloads (Pure)

Abstract

Solid immersion lenses (SILs) are shown to greatly enhance optical spatial resolution when measuring AlGaN/GaN High Electron Mobility Transistors (HEMTs), taking advantage of the high refractive index of the SiC substrates commonly used for these devices. Solid immersion lenses can be applied to techniques such as electroluminescence emission microscopy and Raman thermography, aiding the development device physics models. Focused ion beam milling is used to fabricate solid immersion lenses in SiC substrates with a numerical aperture of 1.3. A lateral spatial resolution of 300 nm is demonstrated at an emission wavelength of 700 nm, and an axial spatial resolution of 1.7 ± 0.3 μm at a laser wavelength of 532 nm is demonstrated; this is an improvement of 2.5× and 5×, respectively, when compared with a conventional 0.5 numerical aperture objective lens without a SIL. These results highlight the benefit of applying the solid immersion lenses technique to the optical characterization of GaN HEMTs. Further improvements may be gained through aberration compensation and increasing the SIL numerical aperture.

Original languageEnglish
Article number144501
Number of pages9
JournalJournal of Applied Physics
Volume118
Issue number14
Early online date8 Oct 2015
DOIs
Publication statusPublished - 14 Oct 2015

Structured keywords

  • CDTR

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