An object of the present invention is to provide a method for comparatively simply selecting polycrystalline silicon suitably used for stably producing single crystal silicon in high yield. According to the present invention, polycrystalline silicon having a maximum surface roughness (Peak-to-Valley) value Rpv of 5000 nm or less, an arithmetic average roughness value Ra of 600 nm or less and a root mean square roughness value Rq of 600 nm or less, the surface roughness values being measured by observing with an atomic force microscope (AFM) the surface of a collected plate-shaped sample, is selected as a raw material for producing single crystal silicon.

Provided is a polycrystalline silicon rod suitable as a raw material for production of single-crystalline silicon. A crystal piece (evaluation sample) is collected from a polycrystalline silicon rod grown by a Siemens method, and a polycrystalline silicon rod in which an area ratio of a crystal grain having a particle size of 100 nm or less is 3% or more is sorted out as the raw material for production of single-crystalline silicon. When single-crystalline silicon is grown by an FZ method using the polycrystalline silicon rod as a raw material, the occurrence of dislocation is remarkably suppressed.

A cleaning method includes a first removal step of causing an inert gas to which a pulsation is applied to flow into an exhaust pipe after a silicon single crystal doped with an n-type dopant is produced, to peel and remove a deposit; and a second removal step of causing an atmospheric air to which no pulsation is applied to flow into the exhaust pipe through a chamber to burn a part of the deposit with the atmospheric air, the part being not removable in the first removal step, and peel and remove a burned substance of the deposit.

A single crystal manufacturing apparatus to grow a single crystal upward from a seed crystal, the apparatus including an insulated space thermally insulated from a space outside the single crystal manufacturing apparatus, an induction heating coil placed outside the insulated space, a thermal insulation plate that divides the insulated space into a first space including a crystal growth region to grow the single crystal and a second space above the first space and includes a hole above the crystal growth region, a heating element that is placed in the second space and generates heat by induction heating using the induction heating coil to heat the inside of the insulated space, and a support shaft to vertically movably support the seed crystal from below.

A deposit removing device disclosed herein removes a deposit that adheres to an exhaust pipe through which gas is exhausted from a chamber that manufactures a semiconductor crystal. The deposit removing device includes: a valve that opens and closes an exhaust outlet that communicates with the exhaust pipe; a sealing cover and a fixed table configured to store the valve, into which an inert gas is introduceable, and configured to isolate the exhaust outlet from the outside; and an exhaust outlet opening/closing portion that includes a cylinder for driving the valve and a cylinder for driving the sealing cover or the fixed table. The cylinder drives the valve to open and close the exhaust outlet, and the cylinder drives the sealing cover or the fixed table to introduce the atmosphere into the sealing cover.

A method for producing a Group III nitride crystal, includes: preparing an RAMO.sub.4 substrate containing a single crystal represented by the general formula RAMO.sub.4 (wherein R represents one or a plurality of trivalent elements selected from a group consisting of Sc, In, Y, and a lanthanoid element, A represents one or a plurality of trivalent elements selected from a group consisting of Fe(III), Ga, and Al, and M represents one or a plurality of divalent elements selected from a group consisting of Mg, Mn, Fe(II), Co, Cu, Zn, and Cd) and having a notch on a side portion thereof; growing a Group III nitride crystal on the RAMO.sub.4 substrate; and cleaving the RAMO.sub.4 substrate from the notch.

There are provided a lithium-containing garnet crystal high in density and ionic conductivity, and an all-solid-state lithium ion secondary battery using the lithium-containing garnet crystal. The lithium-containing garnet crystal has a chemical composition represented by Li.sub.7-xLa.sub.3Zr.sub.2-xTa.sub.xO.sub.12 (0.2≦x≦1), and has a relative density of 99% or higher, belongs to a cubic system, and has a garnet-related structure. The lithium-containing garnet crystal has a lithium ion conductivity of 1.0×10.sup.−3 S/cm or higher. Further, this solid electrolyte material has a lattice constant a of 1.28 nm≦a≦1.30 nm, and lithium ions occupy 96h-sites in the crystal structure. The all-solid-state lithium ion secondary battery has a positive electrode, a negative electrode and a solid electrolyte, and the solid electrolyte is constituted of the lithium-containing garnet crystal according to the present invention.

A crystal material represented by a general formula (1):
(Gd.sub.1-x-y-zLa.sub.xME.sub.yRE.sub.z).sub.2MM.sub.2O.sub.7   (1),
where ME is at least one selected from Y, Yb, Sc, and Lu; RE is Ce or Pr; MM is at least one selected from Si and Ge; and ranges of x, y, and z are represented by the following (i): (i) 0.0≦x+y+z<1.0, 0.05≦x+z<1.0, 0.0≦y<1.0, and 0.0001≦z<0.05 (where, when RE is Ce, y=0 is an exception).

A crystal material represented by a general formula (1):
(Gd.sub.1-x-y-zLa.sub.xME.sub.yRE.sub.z).sub.2MM.sub.2O.sub.7   (1),
where ME is at least one selected from Y, Yb, Sc, and Lu; RE is Ce or Pr; MM is at least one selected from Si and Ge; and ranges of x, y, and z are represented by the following (i): (i) 0.0≦x+y+z<1.0, 0.05≦x+z<1.0, 0.0≦y<1.0, and 0.0001≦z<0.05 (where, when RE is Ce, y=0 is an exception).

A growth chamber or a Czochralski crystal growth station has one or more re-sealable caps that are inserted into the chamber body. An O-ring seals the cap within its mating portion of the chamber body. The re-sealable caps facilitate re-use of the chamber body for a future crystal growth cycle.