Development of a High Lateral Resolution Electron Beam Induced Current Technique for Electrical Characterization of InGa
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L10.10.1
Development of a High Lateral Resolution Electron Beam Induced Current Technique for Electrical Characterization of InGaN-Based Quantum Well Light Emitting Diodes Kristin L. Bunker1, Juan Carlos Gonzalez1, Dale Batchelor1, Terrence J. Stark2, and Phillip E. Russell1,2 1 Analytical Instrumentation Facility and Materials Science and Engineering Department, North Carolina State University, Box 7531, Raleigh, NC 27695 USA 2 Materials Analytical Services, 616 Hutton Street, Suite 101, Raleigh, NC 27606 USA
ABSTRACT Electron Beam Induced Current (EBIC) is a Scanning Electron Microscope (SEM)-based technique that can provide information on the electrical properties of semiconductor materials and devices. This work focuses on the design and implemenation of an EBIC system in a dedicated Scanning Transmission Electron Microscope (STEM). The STEM-EBIC technique was used in the characterization of an Indium Gallium Nitride (InGaN) quantum well Light Emitting Diode (LED). The conventional “H-bar” Transmission Electron Microscopy (TEM) sample preparation method using Focused Ion Beam Micromachining (FIBM) was adapted to create an electron-transparent membrane approximately 300 nm thick on the sample while preserving the electrical activity of the device. A STEM-EBIC sample holder with two insulated electrical feedthroughs making contact to the thinned LED was designed and custom made for these experiments. The simultaneous collection of Z-contrast images, EBIC images, and In and Al elemental images allowed for the determination of the p-n junction location, AlGaN and GaN barrier layers, and the thin InGaN quantum well layer within the device. The relative position of the p-n junction with respect to the thin InGaN quantum well was found to be (19 ± 3) nm from the center of the InGaN quantum well. INTRODUCTION As the solid-state electronics industry continues to shrink the dimensions of electronic devices and enter into the nanotechnology era, the field of analytical techniques for materials and device characterization is presented with new and additional challenges. The structural, chemical, electrical, and optical properties have to be studied with nanometer resolution and higher sensitivity. Therefore, nano-characterization techniques are needed to investigate the properties of new materials and the performance and failure of devices formed from these new materials. Scanning Electron Microscope (SEM)-based Electron Beam Induced Current (EBIC) is a technique that can be used for the electrical characterization of materials and devices. EBIC can provide information on electrically active defects, diffusion of carriers, surface recombination mechanism, bulk recombination mechanism, trapping centers, and especially p-n junction width, position, and homogeneity [1,2,3,4]. However, in the SEMbased EBIC technique, the beam excited volume of electron hole pairs (EHPs) limits the spatial resolution. Therefore, there is a need for a high-resolution EBIC technique. The STEM-based EBIC technique combines a thin sample and a hig
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