Abstract: A rapid thermal processing apparatus and method wherein a transparent (e.g. quartz) vacuum wall is sealed to the process chamber by a radially elastically expandable metallic seal, e.g. a hollow metallic ring with a spring in its core, which has a soft surface portion which deforms inelastically to make a seal.

Abstract: A molecular beam epitaxy system wherein the molybdenum substrate holder and the molybdenum ring which assembles to the substrate holder to hold the wafer are kept in vacuum essentially all the time. Wafers are not pre-mounted to substrate holders, but the wafer mounting step is performed in ultrahigh vacuum after a cassette of wafers has already been loaded and outgassed, under ultrahigh vacuum. Thus, the substrate holder can be outgassed separately at high temperatures, and can remain under high vacuum.

Abstract: A molecular beam epitaxy system wherein the wafer on which epitaxial deposition is to occur is not soldered to a substrate holder. Instead, a substrate holder with a lip approximately as high as the thickness of the wafer is used, and a retaining ring attaches to the substrate holder to hold the wafer in place during the growth cycle. The retaining ring, like the substrate holder, is made of high-purity refractory material, such as arccast molybdenum. The substrate holder and retaining ring are dimensioned to hold the wafer somewhat loosely, to allow for thermal expansion during the cycling up to growth temperature, which is typically about 600.degree. C.