A method for producing Si ingot single crystal including a Si ingot single crystal growing step, a temperature gradient controlling step and a continuous growing step is provided. In the growing step, the Si ingot single crystal is grown in silicon melt in crucible, and the growing step includes providing a low-temperature region in the Si melt and providing a silicon seed to contact the melt surface of the silicon melt to start crystal growth, and silicon single crystal grows along the melt surface of the silicon melt and toward the inside of the silicon melt. In the temperature gradient controlling step, the under-surface temperature gradient of the silicon single crystal is G1, the above-surface temperature gradient of the silicon single crystal is G2, G1 and G2 satisfy: G2/G1<6. The step of controlling the temperature gradient of silicon single crystal is repeated to obtain the Si ingot single crystal.

A method for producing Si ingot single crystal including a Si ingot single crystal growing step, a temperature gradient controlling step and a continuous growing step is provided. In the growing step, the Si ingot single crystal is grown in silicon melt in crucible, and the growing step includes providing a low-temperature region in the Si melt and providing a silicon seed to contact the melt surface of the silicon melt to start crystal growth, and silicon single crystal grows along the melt surface of the silicon melt and toward the inside of the silicon melt. In the temperature gradient controlling step, the under-surface temperature gradient of the silicon single crystal is G1, the above-surface temperature gradient of the silicon single crystal is G2, G1 and G2 satisfy: G2/G1<6. The step of controlling the temperature gradient of silicon single crystal is repeated to obtain the Si ingot single crystal.

A method for preparing a single crystal silicon ingot and a wafer sliced therefrom are provided. The ingots and wafers comprise nitrogen at a concentration of at least about 1×10.sup.14 atoms/cm.sup.3 and/or germanium at a concentration of at least about 1×10.sup.19 atoms/cm.sup.3, interstitial oxygen at a concentration of less than about 6 ppma, and a resistivity of at least about 1000 ohm cm.

A method for preparing a single crystal silicon ingot and a wafer sliced therefrom are provided. The ingots and wafers comprise nitrogen at a concentration of at least about 1×10.sup.14 atoms/cm.sup.3 and/or germanium at a concentration of at least about 1×10.sup.19 atoms/cm.sup.3, interstitial oxygen at a concentration of less than about 6 ppma, and a resistivity of at least about 1000 ohm cm.

A fused quartz crucible for pulling a single crystal of silicon by the Czochralski technique, has an inner side with an inner layer of fused quartz that forms a surface, the inner layer being provided with a crystallization promoter which on heating of the fused quartz crucible during use, in crystal pulling, causes crystallization of fused quartz to form b-cristobalite, wherein the concentration C of synthetically obtained SiO.sub.2 at a distance d from the surface is greater than the concentration of synthetically obtained SiO.sub.2 at a distance d2 from the surface, where d2 is greater than d. Multiple crystals can be grown while maintaining high crystal quality.

A fused quartz crucible for pulling a single crystal of silicon by the Czochralski technique, has an inner side with an inner layer of fused quartz that forms a surface, the inner layer being provided with a crystallization promoter which on heating of the fused quartz crucible during use, in crystal pulling, causes crystallization of fused quartz to form b-cristobalite, wherein the concentration C of synthetically obtained SiO.sub.2 at a distance d from the surface is greater than the concentration of synthetically obtained SiO.sub.2 at a distance d2 from the surface, where d2 is greater than d. Multiple crystals can be grown while maintaining high crystal quality.

A quartz glass crucible 1 includes: a quartz glass crucible body 10 having a cylindrical side wall portion 10a, a curved bottom portion 10b, and a corner portion 10c which has a larger curvature than that of the bottom portion 10b and connects the side wall portion 10a and the bottom portion 10b to each other; and an inner-surface coating film 13A which contains a crystallization accelerator and is formed on an inner surface 10i of the quartz glass crucible body 10, in which the inner surface 10i of the quartz glass crucible body 10 is under compressive stress. The quartz glass crucible has high durability even at a high temperature during a single crystal pull-up step and is capable of reducing a generation ratio of pinholes in a silicon single crystal.

A quartz glass crucible 1 includes: a quartz glass crucible body 10 having a cylindrical side wall portion 10a, a curved bottom portion 10b, and a corner portion 10c which has a larger curvature than that of the bottom portion 10b and connects the side wall portion 10a and the bottom portion 10b to each other; and an inner-surface coating film 13A which contains a crystallization accelerator and is formed on an inner surface 10i of the quartz glass crucible body 10, in which the inner surface 10i of the quartz glass crucible body 10 is under compressive stress. The quartz glass crucible has high durability even at a high temperature during a single crystal pull-up step and is capable of reducing a generation ratio of pinholes in a silicon single crystal.

The present application discloses a gallium arsenide single crystal and preparation method thereof. The gallium arsenide single crystal has a carrier concentration of 1×10.sup.18-4×10.sup.18/cm.sup.3, and a migration rate of 1700-2600 cm.sup.2/v.Math.s; at a same carrier concentration, B atom density in the gallium arsenide single crystal obtained using Si.sub.xAs.sub.y compound as a dopant is at least 20% lower than that obtained using Si substance as a dopant; B content in the gallium arsenide single crystal is 5×10.sup.18/cm.sup.3 or lower. The preparation method for the gallium arsenide single crystal is that, before growth of the gallium arsenide single crystal, the Si.sub.xAs.sub.y compound is distributed into a gallium arsenide polycrystal.

The present application discloses a gallium arsenide single crystal and preparation method thereof. The gallium arsenide single crystal has a carrier concentration of 1×10.sup.18-4×10.sup.18/cm.sup.3, and a migration rate of 1700-2600 cm.sup.2/v.Math.s; at a same carrier concentration, B atom density in the gallium arsenide single crystal obtained using Si.sub.xAs.sub.y compound as a dopant is at least 20% lower than that obtained using Si substance as a dopant; B content in the gallium arsenide single crystal is 5×10.sup.18/cm.sup.3 or lower. The preparation method for the gallium arsenide single crystal is that, before growth of the gallium arsenide single crystal, the Si.sub.xAs.sub.y compound is distributed into a gallium arsenide polycrystal.