Electrical Properties of Polycrystalline MgZnO/ZnO Heterostructure
Date Issued
2010
Date
2010
Author(s)
Chin, Huai-An
Abstract
ZnO has shown great potential for application in optoelectronic devices and its conductivity is one of the key issues in device performances. Previous researches show that polarization effect existing in single-crystalline MgZnO/ZnO heterostructure results in carrier confinement at MgZnO/ZnO interface. The two-dimensional electron gas (2DEG) forming at the interface improves the electrical conductance to two to three orders of magnitude. In this thesis, the polarization effect on the electrical roperties of “polycrystalline“ MgZnO/ZnO heterostructure will be studied. ZnO film is grown by rf-sputtering and post-annealing is introduced to reinforce the grain formation. A thin layer of MgZnO is then deposited upon ZnO at room temperature. The electrical conductance of MgZnO/ZnO shows two to three orders of magnitude of improvement compared to ZnO single layer, confirming that polarization effect enhances electrical properties even in polycrystalline system.
MgZnO:Al is used as modulation doping layer in the modulation doping structure, MgZnO/MgZnO:Al/MgZnO/ZnO, in the hope to introduce carrier from MgZnO:Al into 2DEG confinement region. The result indicates that modulation doping shows strongest improvement when Mg content of MgZnO buffer layer is low; while the improvement is less obvious as the Mg content increases.
The heterostructure can be further applied in high-electron-mobility-transistor.
Subjects
Polarization effect
MgZnO/ZnO
heterostructure
two-dimensional electron gas
Type
thesis
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