Radical generator and molecular beam epitaxy apparatus

A radical generator, comprising:

• a supply tube for supplying a gas;
• a plasma-generating tube which is cylindrical and is made of a dielectric material, the plasma-generating tube comprising a connecting tube continuously extending from an upstream end of the plasma-generating tube as one body, an inner diameter of the connecting tube being smaller than an inner diameter of the plasma-generating tube, and the connecting tube being connected to the supply tube at a downstream end of the supply tube;
• a coil winding around an outer wall of the plasma-generating tube, for generating an inductively coupled plasma in the plasma-generating tube;
• a first electrode comprising a double-pipe cylinder having an inner space in which cooling material can be refluxed and covering the outer wall of the plasma-generating tube and which is disposed between the coil and the supply tube, for generating a first capacitively coupled plasma in the plasma-generating tube and adding the first capacitively coupled plasma to the inductively coupled plasma;
• a plurality of first permanent magnets which are disposed along an outer circumference of a zone of the plasma-generating tube where the first capacitively coupled plasma is generated and which localize the first capacitively coupled plasma to about a cylinder center axis of the plasma-generating tube, wherein respective first permanent magnets have been magnetized in a direction orthogonal to the cylinder center axis of the plasma-generating tube, and a plane proximal to the plasma-generating tube has been magnetized as an N pole or an S pole, and two first permanent magnets adjacent each other have inner planes of different magnetic poles such that an N pole and an S Pole are alternatingly repeated along a circumferential direction of the plasma-generating tube;
• and
• a second electrode comprising a, double-pipe cylinder having an inner space in which cooling material can be refluxed and covering the outer wall of the plasma-generating tube and more proximal to a downstream end of the plasma-generating tube than the coil is, for generating a second capacitively coupled plasma in the plasma-generating tube and adding the second capacitively coupled plasma to the first capacitively coupled plasma and the inductively coupled plasma which are flowing to the downstream of the plasma generating tube.