Percolation Threshold in Superhard Nanocrystalline Transition Metal-Amorphous Silicon Nitride Composites: The Control and Understanding of the Superhardness

1996 ◽  
Vol 457 ◽  
Author(s):  
Stan Vepřek ◽  
S. Christiansen ◽  
M. Albrecht ◽  
H. P. Strunk
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Silicon Nitride ◽  
Transition Metal ◽  
Percolation Threshold ◽  
Amorphous Silicon ◽  
Amorphous Silicon Nitride ◽  
Amorphous Component ◽  
Nanocrystalline Composites

ABSTRACTThe hardness of the recently developed novel superhard nanocrystalline composites exceeds 5000 kg/mm2 (50 GPa) and the elastic modulus 550 GPa. This is due to a special microstructure which is formed when the fraction of the amorphous component reaches the percolation threshold. Experimental data are presented and discussed.

Electronic Structure of Defects in Amorphous Silicon Nitride

1992 ◽  
Vol 284 ◽  
Author(s):  
John Robertson
Keyword(s):  
Electronic Structure ◽  
Silicon Nitride ◽  
Percolation Threshold ◽  
Amorphous Silicon ◽  
Electronic Properties ◽  
Valence Band ◽  
Band Edge ◽  
Valence Band Edge ◽  
Dangling Bonds ◽  
Amorphous Silicon Nitride

ABSTRACTThe paper reviews the electronic properties of defects in amorphous silicon nitride (a-Si3N4) and the hydrogenated alloys a-SiNx:H. The main defects in a-Si3N4 are the Si and N dangling bonds (DBs). The Si DB forms a sp3 state near midgap, while the N DB forms a highly localized pπ level just above the valence band edge. The behaviour of the alloys changes near x ≈ 1.1, the percolation threshold of Si-Si bonds. In the Si-rich alloys, both band edges are Si-like, only Si DBs are seen and their density is controlled by equilibration with weak Si-Si bonds. The x>1.1 alloys behave like silicon nitride; the valence band changes towards N pπ-like, both Si and N DBs can arise, the Si DB can have a high density and prefers to be in its charged diamagnetic configurations.

scholarly journals Hydrogen effects on the thermal conductivity of delocalized vibrational modes in amorphous silicon nitride (a−SiNx:H)

2021 ◽  
Vol 5 (3) ◽  
Author(s):  
Jeffrey L. Braun ◽  
Sean W. King ◽  
Eric R. Hoglund ◽  
Mehrdad Abbasi Gharacheh ◽  
Ethan A. Scott ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Vibrational Modes ◽  
Amorphous Silicon Nitride

scholarly journals Effect of Thermal Annealing on the Photoluminescence of Dense Si Nanodots Embedded in Amorphous Silicon Nitride Films

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 354
Author(s):  
Qianqian Liu ◽  
Xiaoxuan Chen ◽  
Hongliang Li ◽  
Yanqing Guo ◽  
Jie Song ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Thermal Annealing ◽  
Chemical Vapor ◽  
Peak Position ◽  
Excitation Wavelength ◽  
Very High Frequency ◽  
Amorphous Silicon Nitride ◽  
Silicon Nitride Films ◽  
High Frequency Plasma

Luminescent amorphous silicon nitride-containing dense Si nanodots were prepared by using very-high-frequency plasma-enhanced chemical vapor deposition at 250 °C. The influence of thermal annealing on photoluminescence (PL) was studied. Compared with the pristine film, thermal annealing at 1000 °C gave rise to a significant enhancement by more than twofold in terms of PL intensity. The PL featured a nanosecond recombination dynamic. The PL peak position was independent of the excitation wavelength and measured temperatures. By combining the Raman spectra and infrared absorption spectra analyses, the enhanced PL was suggested to be from the increased density of radiative centers related to the Si dangling bonds (K0) and N4+ or N20 as a result of bonding configuration reconstruction.

Kinetics of silicon nitride crystallization in N+-implanted silicon

1989 ◽  
Vol 4 (2) ◽  
pp. 394-398 ◽  
Author(s):  
V. S. Kaushik ◽  
A. K. Datye ◽  
D. L. Kendall ◽  
B. Martinez-Tovar ◽  
D. S. Simons ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Crystalline Silicon ◽  
Wafer Surface ◽  
Amorphous Silicon Nitride ◽  
Silicon Lattice ◽  
Nitrogen Ions ◽  
The Mean ◽  
Nitride Layers ◽  
Kinetics Of

Implantation of nitrogen at 150 KeV and a dose of 1 ⊠ 1018/cm2 into (110) silicon results in the formation of an amorphized layer at the mean ion range, and a deeper tail of nitrogen ions. Annealing studies show that the amorphized layer recrystallizes into a continuous polycrystalline Si3N4 layer after annealing for 1 h at 1200 °C. In contrast, the deeper nitrogen fraction forms discrete precipitates (located 1μm below the wafer surface) in less than 1 min at this temperature. The arcal density of these precipitates is 5 ⊠ 107/cm2 compared with a nuclei density of 1.6 ⊠ 105/cm2 in the amorphized layer at comparable annealing times. These data suggest that the nucleation step limits the recrystallization rate of amorphous silicon nitride to form continuous buried nitride layers. The nitrogen located within the damaged crystalline silicon lattice precipitates very rapidly, yielding semicoherent crystallites of β–Si3N4.

Enhanced crystallization and phase transformation of amorphous silicon nitride under high pressure

2001 ◽  
Vol 16 (1) ◽  
pp. 67-75 ◽  
Author(s):  
Ya-Li Li ◽  
Yong Liang ◽  
Fen Zheng ◽  
Xian-Feng Ma ◽  
Suo-Jing Cui ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Crystallization Temperature ◽  
Amorphous Materials ◽  
Normal Pressure ◽  
Nucleation And Growth ◽  
Amorphous Silicon Nitride ◽  
Amorphous Si

The crystallization and phase transformation of amorphous Si3N4 ceramics under high pressure (1.0–5.0 GPa) between 800 and 1700 °C were investigated. A greatly enhanced crystallization and α–β transformation of the amorphous Si3N4 ceramics were evident under the high pressure, as characterized by that, at 5.0 GPa, the amorphous Si3N4 began to crystallize at a temperature as low as 1000 °C (to transform to a modification). The subsequent a–b transformation occurred completed between 1350 and 1420 °C after only 20 min of pressing at 5.0 GPa. In contrast, under 0.1 MPa N2, the identical amorphous materials were stable up to 1400 °C without detectable crystallization, and only a small amount of a phase was detected at 1500 °C. The crystallization temperature and the a–b transformation temperatures are reduced by 200–350 °C compared to that at normal pressure. The enhanced phase transformations of the amorphous Si3N4 were discussed on the basis of thermodynamic and kinetic consideration of the effects of pressure on nucleation and growth.

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