研究目的
To investigate the effects of buffer layer structure on the crystallographic character of GaAs layers grown on GaP substrates and to develop design principles for buffer layer structures.
研究成果
The experimental results suggested that the GaAs layer is relatively relaxed but contains a greater number of dislocations when smaller layer thicknesses and larger lattice mismatches are introduced in the buffer layer structure. On the other hand, the GaAs layer has a smaller number of dislocations but a rather deformed lattice structure when the buffer layer design is opposite. The proposed parameter is useful for developing design principles of buffer layer structures.
研究不足
The inserted strained-layer superlattices (SLSs) did not work as expected due to deformation of the layer structure during growth, which might be one of the reasons why the SLS structure was not able to reduce the dislocation density in this work.
1:Experimental Design and Method Selection:
GaAs layers were grown on GaP substrates using various buffer layer structures with different lattice constants and thicknesses. The lattice constants were controlled by changing the As/P and In/Ga compound ratios.
2:Sample Selection and Data Sources:
Single crystal GaP wafers with surface orientation (001) ≈ 2o off towards [110] were used as substrates.
3:List of Experimental Equipment and Materials:
An atmospheric-pressure metal–organic vapor phase epitaxy (MOVPE) apparatus with a horizontal quartz reactor was used for growth.
4:Experimental Procedures and Operational Workflow:
The GaP substrates were prepared by degreasing, etching, and rinsing before growth. The growth was performed on a quartz tray without substrate rotation.
5:Data Analysis Methods:
The crystal properties of the grown GaAs layers were characterized with X-ray diffraction, photoluminescence, and etch pit density observations.
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