In this study, we investigated the effect of substrate temperature on the change in structural and morphological properties
of thin film Gallium Arsenide (GaAs) deposited by pulsed laser deposition (PLD) on Silicon (Si) substrate. The growths
were conducted at different substrate temperatures (25º C - 600º C). X-ray Diffraction (XRD), Atomic Force Microscopy
(AFM) and Scanning Electron Microscopy (SEM) were used to study the crystal structure and surface quality of the
films. It was observed that the films were increasingly more crystalline in the (111) orientation and also larger in crystal
grain size with increase in substrate temperature 285º C and above. The deposited GaAs films on Si were smooth, dense
and free of voids, pinholes and cracks for a wide range of temperature.
Several growths of Si nanodots on Si and GaAs substrates were conducted by pulsed laser deposition (PLD) using a KrF
laser of 248nm, 15ns, 12Hz and a Ti-sapphire laser of 800nm, 130fs, 1kHz at 1x10-5mbar vacuum. The laser fluencies on
a Si target were varied from 3 to 32J/cm2 for the nanosecond (ns) PLD growths and 1-2.75J/cm2 for the femtosecond (fs)
PLD. Wide range of nanodots from 20nm to a few micron size droplets were observed from both the ns and fs PLD.
Auger electron spectroscopy of the nanodots was conducted and which indicated that the nanodots were without
A technique using a mask consisting of an array of small holes was used to obtain high density nanodots with uniform
size. The array of 100nm diameter holes was created by E-beam lithography. With this technique we have achieved
100nm Si dots with 300nm spacing between them, with few defects. We have observed that laser fluences closer to the
ablation threshold work better for deposition using the EBL mask. In summary, we have demonstrated the growth of
100nm Si nanodots in an array with very few defects using the EBL masking technique.