Ask the Expert: Materials Characterization of GaN Power Transistors

During this live event we answered pre-submitted questions from our audience about Secondary Ion Mass Spectrometry (SIMS) analysis and Advanced Microscopy of GaN HEMT power transistors. We may also discuss other analytical methods, such as electron microscopy, to provide a more comprehensive answer.

Demand for compound semiconductors (especially III-V materials) has rapidly grown in recent years due to the need for faster transistors with more power, as well as the increased use of lasers in optical networking and sensors. These epitaxially grown materials are almost always complex in layer structure, with varying alloy composition and thin dopant layers. For device performance quality checks, it is essential to have low detection limits for impurities, correct dopant distribution determination and highly accurate concentration calibration. Dopant layer thickness, especially across varying matrix composition, is often measured by SIMS also. However, these needs are challenged by “matrix effects” in these complex multi-layered structures. Therefore, a SIMS method which minimizes these artifacts is important for obtaining reliable results throughout the structure of interest. PCOR-SIMSSM is a point-by-point data correction algorithm, which uses the alloy composition at a given data point for proper calibration of SIMS intensities. This minimizes matrix effects therefore, layer thicknesses and elemental concentrations, most importantly across graded compositions, are determined with much less error.

Current GaN HEMT devices have layers which are ~10nm thick. Therefore, depth resolution of SIMS profiles must be sufficient to detect small variations in these layers. With the use of special analytical protocols to study small changes in growth conditions of 10-30nm near surface layers.

In this webinar we covered:

  • Principles of PCOR-SIMSSM
  • Routine SIMS analyses of GaN HEMT for dopants and impurities
  • Application of PCOR-SIMSSM to characterize 1-20 nm layers
  • Data artifacts caused by defects

Related Resources


  • Temel Buyuklimanli, Ph.D. – Scientific Fellow & Vice President
  • Mike Salmon, Ph.D. – Scientific Fellow, Advanced Imaging
  • Miki Nakayama Ph.D. – Team Leader

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