| 摘要 |
In certain semiconductor devices, an epitaxial layer of an oxide or sulfide, in which the crystal orientation is induced by the substrate, provides improved electrical and optical properties in the device. The formation of epitaxial oxide or sulfide layers requires high temperatures or generates charged particles or high energy radiation that damage the substrate and prevent optimum electrical performance of the device. This problem is overcome by exposing the substrate (20) at a low temperature to a chosen vapor phase reactant (from chamber 26) in the presence of neutral, charge-free oxygen atoms or sulfur atoms to produce a reaction between the atomic species and the vapor phase reactant to form the desired oxide or sulfide and induce the crystalline growth thereof as an epitaxial layer on the surface of the substrate (20). The atomic oxygen or the atomic sulfur is formed at a low temperature by the photochemical dissociation of a selected oxygen-containing precursor or a selected sulfur-containing precursor, respectively, (from chamber 28) by radiation of a selected wavelength (from means 16). Epitaxial oxides, such as epitaxial zinc oxide on a sapphire substrate, are useful for forming active optical waveguide structures and active acoustooptical devices. An epitaxial sulfide, such as lead sulfide on a silicon substrate, is useful as the active element in infrared detectors and infrared charge-coupled devices. |
