Abstract: This apparatus comprises a reactor having an inner container made of quartz, a transparent quartz window at the upper end of said reactor, a gas supply pipe for supplying a reactive gas into said reactor and an exhaust pipe for exhausting the gas remaining in the reactor. The apparatus also comprises an infrared lamp house rotatably mounted over the quartz window, and having therein a multiplicity of infrared lamps and a transparent quartz window at the lower end of the lamp house facing the quartz window of the reactor. Since the semiconductor substrate in the reactor is uniformly heated by the isolated lamp house, it is not subjected to dust that can be given off from the rotating lamp house, nor to the turbulence of the reactive gas, thereby allowing uniform growth of a semiconductor crystal on the substrate.