Growth and characterization of II-VI semiconductors for photonic device fabrication.

摘要

This work involved the growth and characterization of mismatched heteroepitaixal II-VI semiconductors on GaAs(001) and InP(001) substrates using photo assisted Metal Organic Vapor Phase Epitaxy (MOVPE). These materials are of interest in applications like projection TV, pointing and alignment devices, and plastic fiber communication.; The growth and the compositional control of ZnSe1-xTe x was achieved on the InGaAs/InP(001) and GaAs(001) substrates. Further the growth of Zn1-xCdxSe and ZnS1-xTe x on InGaAs/InP(001) using MOVPE is also demonstrated.; The compositional and the structural data were obtained using a Bartels High Resolution X-Ray diffractometer (HRXRD). The growth temperature and the photo irradiation are found to play a significant role in determining the composition as well as the growth rate of ZnSe1-xTex. P-type doping was achieved using tetiarybutylamine (TBA) as a source for nitrogen and is measured using Hall-effect method. Results indicate low p-type concentrations due to heavy nitrogen compensation. The optical properties were obtained by low temperature photoluminescence experiments. Results indicated significant departure of the near band emission from the reported bandgap values.; The strain relaxation as a function of the mismatch between the epitaxial layer and substrate was studied for the case of ZnSe1-xTe x on InGaAs/InP. The kinetic barrier of the dislocations played a significant role in the strain relaxation. A systematic study of the asymmetry in the dislocation densities along different azimuthal directions in the case of ZnSe/GaAs(001) was carried out. Results indicate more dislocations with the line vectors of type [110] than the [11¯0] type. This indicates an asymmetry in the dislocation densities along two inplane directions. A quantitative model was developed to explain these results and to calculate the dislocation densities along the two in-plane directions.