TY - JOUR
T1 - Structural characterization of strained AlGaN layers in different Al content AlGaN/GaN heterostructures and its effect on two-dimensional elctron transport porperties
AU - Miyoshi, Makoto
AU - Egawa, Takashi
AU - Ishikawa, Hiroyasu
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2005
Y1 - 2005
N2 - Different Al content AlGaNGaN two-dimensional-electron-gas (2DEG) structures were grown on 100-mm -diam sapphire substrates by metalorganic vapor phase epitaxy (MOVPE). The structural properties of AlGaN layers, such as alloy composition, layer thickness, tensile strain, in-plane stress, crystal quality, and band gap energy, were investigated in detail mainly by x-ray diffraction and spectroscopic ellipsometry. Correspondingly, the electron transport properties of these epilayers were theoretically as well as experimentally studied, taking into account the structural characterization results. Hall effect measurements showed that 2DEG density linearly increases with increasing Al content and that low-temperature 2DEG mobility largely decreases with the increase of Al content. The calculated results demonstrated that interface roughness scattering is largely enhanced with increasing Al content and has a strong impact on low-temperature 2DEG mobilities in high Al content samples. This is because the roughness of the interface between GaN and AlGaN layers increases with Al content. This calculated result is consistent with the experimental result that the surface of MOVPE-grown samples exhibited poor qualities with increasing Al content. The degradation of the surface and/or interface is associated with the increased strain in AlGaN layers.
AB - Different Al content AlGaNGaN two-dimensional-electron-gas (2DEG) structures were grown on 100-mm -diam sapphire substrates by metalorganic vapor phase epitaxy (MOVPE). The structural properties of AlGaN layers, such as alloy composition, layer thickness, tensile strain, in-plane stress, crystal quality, and band gap energy, were investigated in detail mainly by x-ray diffraction and spectroscopic ellipsometry. Correspondingly, the electron transport properties of these epilayers were theoretically as well as experimentally studied, taking into account the structural characterization results. Hall effect measurements showed that 2DEG density linearly increases with increasing Al content and that low-temperature 2DEG mobility largely decreases with the increase of Al content. The calculated results demonstrated that interface roughness scattering is largely enhanced with increasing Al content and has a strong impact on low-temperature 2DEG mobilities in high Al content samples. This is because the roughness of the interface between GaN and AlGaN layers increases with Al content. This calculated result is consistent with the experimental result that the surface of MOVPE-grown samples exhibited poor qualities with increasing Al content. The degradation of the surface and/or interface is associated with the increased strain in AlGaN layers.
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U2 - 10.1116/1.1993619
DO - 10.1116/1.1993619
M3 - Article
AN - SCOPUS:31144465903
VL - 23
SP - 1527
EP - 1531
JO - Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
JF - Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
SN - 1071-1023
IS - 4
ER -