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Self-assembly and photoluminescence properties of SiC quantum dots
Author
Ng, Vic Meng
Supervisor
Xu, Shuyan
Abstract
Zero-dimensional quantum dots (QDs) have attracted much interest for its potential device applications. With its wide band gap, excellent thermal properties and large bonding energy, Sic QDs offer great applications in optoelectronic blue and ultra-violet wavelength emissions operating at high power levels, high temperatures and caustic environments.
In this work self-assembled Sic QDs is successfully grown on an A1N buffer layer on Si (100) substrates using a radio frequency (RF) magnetron sputtering system. Room temperature photoluminescence (PL) measurements using a 5 14.5 nm Ar+laser source reveal PL peaks to vary between 615 - 720 nm. PL spectra are observed to be inhomogeneously broadened. Field emission scanning electron microscopy (SEM) images illustrate the size, distribution, coalescence and morphology of the SIC QDs.
For Sic QDs deposited on the buffer layer, PL intensity is improved and dot sizes are enlarged with deposition time. Further investigations reveal that an increase in deposition time increases dot coalescence and reduces surface dot density. SEM and PL investigations reveal two correlations: lower surface dot density correlates with diminished PL bandwidth and increased coalescence of QDs correlates with higher PL intensity. PL intensity is also found to improve with deposition temperature and upon annealing.
For SIC QDs deposited up to 30 minutes, a PL peak red-shifl attributed to QD size increase is observed. Nonetheless, PL peak blue-shift is observed with increase in either SIC deposition time beyond 30 minutes and N1(dopant) flow rate. Other than its inherent small dimensions, broad XRD peaks suggest the SIC QDs have an amorphous structure. The PL peak blue-shift could possibly be due to diminishing amorphous Sic fraction.
Further investigations reveal the AIN buffer layer increases dot coalescence. Regardless of Sic deposition time, the buffer layer is found to pre-dominantly enhance PL intensity. Thus, a correlation between dot agglomeration and PL intensity is also observed. Further investigations show deposition time improves PL intensity of QDs deposited directly on the Si substrate. SEM images reveal that QD sizes increase with deposition time. TEM images agree with the latter morphological observations.
In this work self-assembled Sic QDs is successfully grown on an A1N buffer layer on Si (100) substrates using a radio frequency (RF) magnetron sputtering system. Room temperature photoluminescence (PL) measurements using a 5 14.5 nm Ar+laser source reveal PL peaks to vary between 615 - 720 nm. PL spectra are observed to be inhomogeneously broadened. Field emission scanning electron microscopy (SEM) images illustrate the size, distribution, coalescence and morphology of the SIC QDs.
For Sic QDs deposited on the buffer layer, PL intensity is improved and dot sizes are enlarged with deposition time. Further investigations reveal that an increase in deposition time increases dot coalescence and reduces surface dot density. SEM and PL investigations reveal two correlations: lower surface dot density correlates with diminished PL bandwidth and increased coalescence of QDs correlates with higher PL intensity. PL intensity is also found to improve with deposition temperature and upon annealing.
For SIC QDs deposited up to 30 minutes, a PL peak red-shifl attributed to QD size increase is observed. Nonetheless, PL peak blue-shift is observed with increase in either SIC deposition time beyond 30 minutes and N1(dopant) flow rate. Other than its inherent small dimensions, broad XRD peaks suggest the SIC QDs have an amorphous structure. The PL peak blue-shift could possibly be due to diminishing amorphous Sic fraction.
Further investigations reveal the AIN buffer layer increases dot coalescence. Regardless of Sic deposition time, the buffer layer is found to pre-dominantly enhance PL intensity. Thus, a correlation between dot agglomeration and PL intensity is also observed. Further investigations show deposition time improves PL intensity of QDs deposited directly on the Si substrate. SEM images reveal that QD sizes increase with deposition time. TEM images agree with the latter morphological observations.
Date Issued
2004
Call Number
TK7874.88 Ng
Date Submitted
2004