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      Variable temperature-scanning Hall probe microscopy with GaN/AlGaN two-dimensional electron gas (2DEG) micro Hall sensors in 4.2-425 K range using novel quartz tuning fork AFM feedback

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      Author(s)
      Akram, Rizwan
      Dede, Münir
      Oral, Ahmet
      Date
      2008
      Source Title
      IEEE Transactions on Magnetics
      Print ISSN
      0018-9464
      Publisher
      IEEE
      Volume
      44
      Issue
      11
      Pages
      3255 - 3260
      Language
      English
      Type
      Conference Paper
      Item Usage Stats
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      Abstract
      In this paper, we present the fabrication and variable temperature (VT) operation of Hall sensors, based on GaN/AlGaN heterostructure with a two-dimensional electron gas (2DEG) as an active layer, integrated with quartz tuning fork (QTF) in atomic force-guided (AFM) scanning Hall probe microscopy (SHPM). Physical strength and a wide bandgap of GaN/AlGaN heterostructure makes it a better choice to be used for SHPM at elevated temperatures, compared to other compound semiconductors (AlGaAs/GaAs and InSb), which are unstable due to their narrower bandgap and physical degradation at high temperatures. GaN/AlGaN micro Hall probes were produced using optical lithography and reactive ion etching. The active area, Hall coefficient, carrier concentration, and series resistance of the Hall sensors were ∼1 × 1 μm, 10 mΩ/G at 4.2 K, 6.3 × 10 12 cm -2 and 12 kΩ at room temperature and 7 mΩ/G, 8.9 × 10 12 cm -2 and 24 kΩ at 400 K, respectively. A novel method of AFM feedback using QTF has been adopted. This method provides an advantage over scanning tunneling-guided feedback, which limits the operation of SHPM the conductive samples and failure of feedback due to high leakage currents at high temperatures. Simultaneous scans of magnetic and topographic data at various pressures (from atmospheric pressure to high vacuum) from 4. to 425K will be presented for different samples to illustrate the capability of GaN/AlGaN Hall sensors in VT-SHPM.
      Keywords
      Atomic force microscopy (AFM)
      GaN/AlGaN heterostructure
      Hall probe
      Quartz tuning fork (QTF)
      Scanning Hall probe microscopy (SHPM)
      Compound semiconductors
      Elevated temperature
      Leakage currents
      Permalink
      http://hdl.handle.net/11693/26850
      Published Version (Please cite this version)
      http://dx.doi.org/10.1109/TMAG.2008.2001622
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