Citation
Yap, Siew Hong
(2005)
Carrier Transport and I-V Characterization of Si, An/Si and Ag/Si Silicides Using Photoacoustic and Four Point Probe Techniques.
Masters thesis, Universiti Putra Malaysia.
Abstract
The AdSi and Ag/Si systems have been studied extensively due to the importance of
carrier transport and I-V characterization of metal silicide compounds in
microelectronic applications. In this study, the metal thin film was deposited on the
polished Si substrate and annealed in air environment. Open photoacoustic cell and
four point probe techques were applied for carrier transport and I-V
characterization respectively of Si substrate, AulSi, Ag/Si interface system at room
temperature. X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM)
analysis were used to confirm the silicide formation and sample surface
microstructure respectively.
The thermal diffusivity and diffusion coefficient of Si substrate were found
independent of the surface condition. The surface recombination velocity values for
the polished surface were in the range of 392.3 cm/s to 458.0 cm/s and the band to
band recombination lifetime for polished surface ranged from 11.57 ps to 17.28 ps.
For the annealed Au(150 nm)ln-Si sample, gold silicide clusters were agglomerated
out to the sample surface while gold clusters were shrunk. The silicide clusters have caused the surface and bulk recombination process to dominate. Au8 9 and Au7Si
(622) silicides were formed on Adp-Si sample after annealing at temperatures of 363
"C and 800 "C respectively. The surface recombination velocity increased from 408.0
cmls to 596.8 crnls as the annealing temperature increased. The surface and bulk
recombination process increased with the formation of AqSi silicide, which
indicates that Au7Si (622) silicide was present as n-conducting that in contact with
the p-Si substrate to form p-n junction characterization (Schottky curve) at the
annealing temperature of 800 "C.
In this investigation, we found a new approach for the Ag miscible with Si to form
the silver silicide compounds for the Aglp-Si system. In the approach, the suitable
type of the Si substrate, deposited thin film thickness, annealing temperature and
time were the main factors for the chemical reaction within Ag and Si. We also
found a transition from 2-D to 3-D growth (Stranski-Krastanov mode) of silver and
silver silicide clusters. For AgJp-Si system, the thermal diffusivity was in the range
of 0.800 cm2/s to 0.850 cm2/s. The increased surface and bulk recombination process
was due to the formation of silver silicide on the sample surface. The I-V
characteristic illustrated an ideal diode junction and Schottky curve for annealed
Ag(100 nm)/p-Si and annealed Ag(150 nm)/pSi respectively. We suggested that
Ag3Si silicide became n-conducting on the p-type Si which responsible in forming
Schottky diode junction. The surface recombination velocity and band to band
recombination lifetime of annealed Ag(150 nm)/n-Si sample was 428.7 cmls and
8.86 p respectively. Both annealed Agln-Si samples exhibited linear I-V relation in
the range of -40 mV to 90 mV.
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