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A method to control the si ze of nanoscale silicon grown in thermally annealed hydrogenated amorphous silico n (a-Si∶H) films is reported. Using the characterizing techniques of micro-Ra man scattering, X-ray diffraction and computer simulation, it is found that the sizes of the formed silicon particles change with the temperature rising rate i n thermally annealing the a-Si∶H films. When the a-Si∶H films have been anne aled with high rising rate( ~100 ℃/s), the sizes of nanoscale silicon particle s are in the range of 1.6~15 nm. On the other hand, if the a-Si∶H films have been annealed with low temperature rising rate(~1 ℃/s), the sizes of nanoscale silicon particles are in the range of 23~46 nm. Based on the theory of crystal nucleation and growth, the effect of temperature rising rate on the sizes of th e formed silicon particles is discussed. Under high power laser irradiation, in situ nanocrystallization and subsequent nc-Si clusters are small enough for vis ible light emission, authors have not detected any visible photoluminescence(PL) from these nc-Si clusters before surface passivation. After electrochemical ox idization in hydrofluoric acid, however, intense red PL has been detected. Cycli c hydrofluoric oxidization and air exposure can cause subsequent blue shift in t he red emission. The importance of surface passivation and quantum confinement i n the visible emissions has been discussed.
A method to control the ze ze of nanoscale silicon grown in thermally annealed hydrogenated amorphous silico n (a-Si: H) films is reported. Using the characterizing techniques of micro-Ra man scattering, X-ray diffraction and computer simulation, it is found that the sizes of the formed silicon particles change with the temperature rising rate in thermally annealing the a-Si: H films. When the a-Si: H films have been annealed with high rising rate (~100 ° C./s), the sizes of nanoscale silicon particles are in the range of 1.6 ~ 15 nm. On the other hand, if the a-Si: H films have been annealed with low temperature rising rate (~ 1 ° C./s), the sizes of nanoscale Based on the theory of crystal nucleation and growth, the effect of temperature rising rate on the sizes of th e formed silicon particles is discussed. Under high power laser irradiation, in situ nanocrystallization and subsequent nc-Si clusters are small enough for vis ible light emission, authors have not detected any visible photoluminescence (PL) from these nc-Si clusters before surface passivation. After electrochemical oxidization in hydrofluoric acid, however, intense red PL has been detected. Cycli c hydrofluoric oxidization and air exposure can cause subsequent blue shift in t he red emission. The importance of surface passivation and quantum confinement in the visible emissions has been discussed.