STUDY ON DEFECT FORMATION IN BULK CRYSTAL FOR ELECTRONIC DEVICES

Molecular dynamics simulation was carried out to estimate diffusion constants and mechanism of pointdefects such as a single vacancy and a self-interstitial atom under hydrostatic pressure.Stillinger-Weber potential used as a model potential，这是一个widely accepted for modeling of silicon crystals and melts.我们拥有追随者results on a self-interstitial atom from the calculation. 1) Diffusion constants ofself-interstitial are almost independent of pressure within a range from -50 to + 50k bar. 2self-interstitial atom diffuses with a formation of dumbbell结构which is aligned in [110] direction. For single vacancythe following were clarified. 1) Diffusion constants of vacancy are also independent of pressure2) a vacancy diffuses with a switching mechanism to nearestneighbor lattice site.Molecular dynamic simulation of an oxygen atom in silicon crystal and the melt这也是在oxygen在melt. the simulation using obtain diffusion constants of oxygenmixed potential in the melt in which an oxygen atom and 216 silicon atoms taken into accountVibration frequencies of oxygen and vacancy-oxygen (V-O) pair in the crystalhave been calculated. calculated frequency of oxygen and V-O pair were 1000 and 800 cmrespectively,while experimental results which were obtained from Fourier transform spectra of infrared absorption（FTIR） are 1100 and 830 cm我们D1-1我们D1，Oxygen diffusion constant obtained in elevated temperature of 1700k . Calculateddiffusion constant of oxygen in the melt was 2x10 - 1-4 - D1 cm - D12 - D1/sec。

Molecular dynamics simulation was carried out to estimate diffusion constants and mechanism of point defects such as a single vacancy and a self-interstitial atom under hydrostatic pressure. Stillinger-Weber potential was used as a model potential, which is widely accepted for modeling of silicon crystals and melts. We obtained the following results on a self-interstitial atom from the calculation. 1) Diffusion constants of self-interstitial are almost independent of pressure within a range from -50 to +50 k bar. 2) A self-interstitial atom diffuses with a formation of dumbbell structure, which is aligned in [110] direction. For single vacancy, the following were clarified. 1) Diffusion constants of vacancy are also independent of pressure within a range from -40 to +40 k bar. 2) A vacancy diffuses with a switching mechanism to nearest neighbor lattice site.Molecular dynamic simulation of an oxygen atom in silicon crystal and the melt was also carried out to obtain diffusion constants of oxygen in the melt. The simulation using mixed potential in the melt in which an oxygen atom and 216 silicon atoms were taken into account has been carried out. Vibration frequencies of oxygen and vacancy-oxygen (V-O) pair in the crystal have been calculated. Calculated frequency of oxygen and V-O pair were 1000 and 800 cmィイD1-1ィエD1, respectively, while experimental results which were obtained from Fourier transform spectra of infrared absorption (FTIR) are 1100 and 830 cmィイD1-1ィエD1, respectively. Oxygen diffusion constant was obtained in elevated temperature of 1700 K. Calculated diffusion constant of oxygen in the melt was 2x10ィイD1-4ィエD1 cmィイD12ィエD1/sec.