K Tanahashi

Concentration of point defects changed by thermal stress in growing CZ silicon crystal: effect of the growth rate

Behavior of point defects under thermal stress in growing Czochralski (CZ) silicon is theoretically examined. The changes in point defect concentration by the thermal stress depending on the growth rate are quantitatively estimated, and their contributions to the formation of secondary defects are discussed.

Dependence of temperature gradient on growth rate in CZ silicon

The dependence of temperature gradient in CZ-Si crystal on the growth rate is examined by analyzing the experimental result where growth rate alone was varied without changing any other conditions. Unreported data are reproduced using the heat balance equation at the interface. It is shown that the temperature gradient increases linearly with the growth rate. The mechanism is discussed in terms of the heat flow and the interface shape.

Equilibrium concentration of vacancies under the anisotropic stress field around and impurity

Equilibrium concentration of vacancies under the anisotropic stress field around an impurity is investigated. The anisotropy of the work by anisotropic stress is considered. Threshold change of equilibrium concentration of vacancies corresponding to the reported change of void density by B and Sb doping is found. By using this, we can predict the void density change in doped Si.

Effect of stress by dopants and nitrogen on grown-in defects in silicon

We analyze the defect density change caused by B and Sb doping and the determination of configuration of doped N in silicon from the viewpoint of stress accompanied by doping. The former is phenomenologically analyzed by the size-effect model and the threshold point defect concentration change for void density change is estimated. The latter is analyzed using the valence force field model and the atomic strain energy is calculated. The role of strain energy and unpaired electron in determining the structure is discussed.

The measurement of work function on GaAs (0 0 1) surface during MBE growth by scanning electron microscopy

Secondary electron (SE) intensity was measured in situ during Ga supply on the molecular beam epitaxy (MBE) grown GaAs (0 0 1) surface using scanning electron microsope-MBE hybrid system. SE intensity changed in the opposite way to the reported work function change and the correspondence was excellent. This is promising for in situ, nondestructive determination of local work function during MBE growth or nanometer device process in vacuum.