Vapor phase growth system and method of producing epitaxial wafer

A vapor phase growth system that grows a semiconductor single-crystal thin film on a main surface of a single-crystal substrate, the vapor phase growth system comprising:

• a reaction vessel body including a gas inlet port on a first end side and a gas outlet port on a second end side in a horizontal direction, wherein the reaction vessel body is configured such that the single-crystal substrate is substantially horizontally and rotationally held on a disk-shaped susceptor, which is rotationally driven in an inner space of the reaction vessel body, and a source gas that forms a semiconductor single-crystal thin film is introduced into the reaction vessel body through the gas inlet port, flows along the main surface of the single-crystal substrate, and is discharged through the gas outlet port, and a preheating ring is arranged to surround the susceptor;
• a susceptor position changing mechanism that changes a height position of holding the susceptor in the reaction vessel body based on raising and lowering of the susceptor to change and set a height dimension of a source gas distribution space formed between the main surface of the single-crystal substrate mounted on the susceptor and a lower surface of a ceiling plate of the reaction vessel body in a stepwise or non-stepwise manner;
• and
• a preheating ring position changing mechanism that changes a height position of holding the preheating ring in the reaction vessel body based on raising and lowering of the preheating ring in accordance with the change in the height position of holding the susceptor;
• the preheating ring position changing mechanism includes a lift sleeve coaxially positioned outside the rotary shaft member and along an axis of the rotary shaft member while allowing the rotary shaft member to be rotationally driven, a coupling member that couples the lift sleeve to the preheating ring, and a lifting driving unit that raises and lowers the lift sleeve and the coupling member in an integrated manner.