Publications by April S. Brown.

Papers Published

  1. Gon Namkoong and Doolittle, W.A. and Brown, A.S. and Losurdo, M. and Giangregorio, M.M. and Bruno, G., Effect of buffer design on AlGaN/AlN/GaN heterostructures by MBE, GaN and Related Alloys - 2003 Symposium (Mater. Res. Soc. Symposium Proceedings Vol.798) (2004), pp. 359 - 64 .
    (last updated on 2007/04/14)

    Abstract:
    The effect of the buffer layers on the subsequent GaN epitaxial layers and electrical properties of AlGaN/AlN/GaN heterojunction structures nitrided at various temperatures was investigated. For AlN buffer layers, two different growth conditions of AlN buffer layers were introduced to avoid Al droplets. We found that etch pit density and structural quality of GaN epitaxial layer strongly depends on the growth conditions of AlN buffer layers. When using a double buffer layer (low temperature GaN on high temperature AlN) for 200 °C nitridation, the etch pit density was measured to high 107 cm-2 in GaN epitaxial layers. Furthermore, we observed that electrical properties of AlGaN/AlN/GaN heterostructures depend on growth conditions of buffer layers and nitridation temperatures. The mobility in Al0.33Ga0.67N/AlN/GaN structures grown on single AlN buffer layers for 200 °C nitridation were 1300 cm2/Vs at a sheet charge of 1.6 × 1013 cm-2. Using the double buffer layer for 200 °C nitridation, the mobility increased to 1587 cm2/Vs with a sheet charge of 1.25 × 1013 cm-2

    Keywords:
    aluminium compounds;gallium compounds;III-V semiconductors;molecular beam epitaxial growth;semiconductor epitaxial layers;semiconductor growth;semiconductor heterojunctions;surface topography;