Characterization of AlGaAs/InGaAs/GaAs Heteroepitaxial Layers by Transmission Electron Microscopy and Energy Dispersive Spectroscopy

1992 ◽  
Vol 281 ◽  
Author(s):  
R. S. Rai ◽  
J. M. Tartaglia ◽  
W. E. Quinn ◽  
D. C. Martel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Dispersive Spectroscopy ◽  
Molecular Beam ◽  
Energy Dispersive ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Periodic Striation ◽  
Heteroepitaxial Layers

ABSTRACTAlGaAs/InGaAs/GaAs heteroepitaxial layers grown by molecular beam epitaxy were studied by cross-sectional transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). The presence of waviness/roughness, fine periodic striation contrast due to Al composition oscillations, and defects were observed by TEM in selected samples. EDS on the TEM was of limited utility in determining the composition of thin epitaxial layers and in comparing the composition near and away from a defect. Arguments are presented to rationalize these results.

scholarly journals Structural Property Study for GeSn Thin Films

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3645
Author(s):  
Liyao Zhang ◽  
Yuxin Song ◽  
Nils von den Driesch ◽  
Zhenpu Zhang ◽  
Dan Buca ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
Threading Dislocations ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron

The structural properties of GeSn thin films with different Sn concentrations and thicknesses grown on Ge (001) by molecular beam epitaxy (MBE) and on Ge-buffered Si (001) wafers by chemical vapor deposition (CVD) were analyzed through high resolution X-ray diffraction and cross-sectional transmission electron microscopy. Two-dimensional reciprocal space maps around the asymmetric (224) reflection were collected by X-ray diffraction for both the whole structures and the GeSn epilayers. The broadenings of the features of the GeSn epilayers with different relaxations in the ω direction, along the ω-2θ direction and parallel to the surface were investigated. The dislocations were identified by transmission electron microscopy. Threading dislocations were found in MBE grown GeSn layers, but not in the CVD grown ones. The point defects and dislocations were two possible reasons for the poor optical properties in the GeSn alloys grown by MBE.

Characterization of zinc diffusion induced disordering in GaAs/AlGaAs multiquantum well structures by Transmission Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 734-735
Author(s):  
B. Bourqui ◽  
P. A. Buffat ◽  
J.D. Ganière ◽  
F. K. Reinhart
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Multilayered Structures ◽  
Transmission Electron ◽  
Zinc Diffusion ◽  
Secondary Ion ◽  
Diffusion Of Impurities ◽  
Multiquantum Well

Diffusion of impurities, such as zinc or silicon, enhances the intermixing of Ga-Al atoms at GaAs/AlGaAs interfaces. This process is useful to modify the bandedge properties of multilayered structures such as (AlxGa1-xAs/GaAs). Important technological applications are due to this effect. Information about electronic states of the disordered structure is directly obtained by photoluminescence. The impurity induced disordering depth is, usually, estimated either by scanning electron microscopy (SEM) or by secondary ion mass spectroscopy (SIMS). We used transmission electron microscopy on wedge shaped specimen (WTEM) is used to obtain local information on the disordering depth and to check the chemical homogeneities of the diffused samples.The multiquantum well structures (MQW) were grown by molecular beam epitaxy (MBE) on n doped [001] substrate at surface temperature of 600 °C. A specimen structure is given in Figure 1. Zinc diffusions were performed by using the sealed quartz tube method at 575°C. The ZnAs2 source provide sufficient partial pressure of arsine to maintain the surface at equilibrium.

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