Low defect density vacancy dominated silicon

A single crystal silicon ingot having a central axis, a seed-cone, an end-cone, and a constant diameter portion between the seed-cone and the end-cone having a circumferential edge and a radius extending from the central axis to the circumferential edge, the single crystal silicon ingot being characterized in that after the ingot is grown and cooled from the solidification temperature, the constant diameter portion contains a first axially symmetric region in which vacancies are the predominant intrinsic point defect and which is substantially free of agglomerated intrinsic point defects wherein the first axially symmetric region comprises the central axis or has a width of at least about 15 mm and has a length as measured along the central axis of at least about 20% of the length of the constant diameter portion of the ingot.

A process for growing a single crystal silicon ingot in which the ingot comprises a central axis, a seed-cone, an end-cone and a constant diameter portion between the seed-cone and the end-cone having a circumferential edge and a radius extending from the central axis to the circumferential edge, the ingot being grown from a silicon melt and then cooled from the solidification temperature in accordance with the Czochralski method, the process comprising

• controlling a growth velocity, v, and an average axial temperature gradient, G.sub.0, during the growth of the constant diameter portion of the crystal over the temperature range from solidification to a temperature of no less than about 1325.degree. C., to cause the formation of a first axially symmetrical region in which vacancies, upon cooling of the ingot from the solidification temperature, are the predominant intrinsic point defect and which is substantially free of agglomerated intrinsic point defects wherein the first axially symmetric region has a width of at least about 15 mm or contains the central axis.