Ask the Expert: Materials Characterization of GaN Power Transistors

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-SIMS^SM 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.