Size quantization effect in GaAs nanocrystals

GaAs nanocrystals have been synthesized by an electrochemical route from the acidic solutions of metallic gallium and arsenic oxide. Structural analysis by transmission electron microscopy (TEM), reveales the presence of orthorhombic phase, in contrast to the usual cubic phase of bulk GaAs. Well separated GaAs nanocrystals having sizes in the range of 7 to View the MathML source are identified in the TEM micrograph. Optical absorption shows a strong excitonic absorption band on account of quantum size effect associated with GaAs nanocrystals. Photoluminescence, recorded at View the MathML source under ultraviolet excitation View the MathML source, shows the HOMO-LUMO transition band as well as the red shifted bands. Micro-Raman analysis shows a phonon mode centered at View the MathML source associated with a point defect.