Abstract: A semiconductor wafer with a front surface and a back surface and an epitaxial layer of semiconducting material deposited on the front surface, wherein the surface of the epitaxial layer has a maximum density of 0.14 localized light scatterers per cm2 with a cross section of greater than or equal to 0.12 ?m, and the front surface of the semiconductor wafer, prior to the deposition of the epitaxial layer, has a surface roughness of 0.05 to 0.29 nm RMS, measured by AFM on a 1 ?m×1 ?m reference area. There is also a process for producing a semiconductor wafer with a front surface and a back surface and an epitaxial layer of semiconducting material deposited on the front surface.

Abstract: A process for epitaxially coating the front surface of a semiconductor wafer in a CVD reactor, the front surface of the semiconductor wafer being exposed to a process gas which contains a source gas and a carrier gas, and the back surface of the semiconductor wafer being exposed to a displacement gas, wherein the displacement gas contains no more than 5% by volume of hydrogen, with the result that diffusion of dopants out of the back surface of the semiconductor wafer, which is intensified by hydrogen, is substantially avoided. With this process, it is possible to produce a semiconductor wafer with a substrate resistivity of ?100 m?cm and a resistivity of the epitaxial layer of >1 ?cm without back-surface coating, the epitaxial layer of which semiconductor wafer has a resistance inhomogeneity of <10%.

Abstract: A process for epitaxially coating the front surface of a semiconductor wafer in a CVD reactor, the front surface of the semiconductor wafer being exposed to a process gas which contains a source gas and a carrier gas, and the back surface of the semiconductor wafer being exposed to a displacement gas, wherein the displacement gas contains no more than 5% by volume of hydrogen, with the result that diffusion of dopants out of the back surface of the semiconductor wafer, which is intensified by hydrogen, is substantially avoided. With this process, it is possible to produce a semiconductor wafer with a substrate resistivity of ?100 m?cm and a resistivity of the epitaxial layer of >1 ?cm without back-surface coating, the epitaxial layer of which semiconductor wafer has a resistance inhomogeneity of <10%.

Abstract: A semiconductor wafer with a front surface and a back surface and an epitaxial layer of semiconducting material deposited on the front surface, wherein the surface of the epitaxial layer has a maximum density of 0.14 localized light scatterers per cm2 with a cross section of greater than or equal to 0.12 &mgr;m, and the front surface of the semiconductor wafer, prior to the deposition of the epitaxial layer, has a surface roughness of 0.05 to 0.29 nm RMS, measured by AFM on a 1 &mgr;m×1 &mgr;m reference area. There is also a process for producing a semiconductor wafer with a front surface and a back surface and an epitaxial layer of semiconducting material deposited on the front surface.

Abstract: A process for epitaxially coating the front surface of a semiconductor wafer in a CVD reactor, the front surface of the semiconductor wafer being exposed to a process gas which contains a source gas and a carrier gas, and the back surface of the semiconductor wafer being exposed to a displacement gas, wherein the displacement gas contains no more than 5% by volume of hydrogen, with the result that diffusion of dopants out of the back surface of the semiconductor wafer, which is intensified by hydrogen, is substantially avoided. With this process, it is possible to produce a semiconductor wafer with a substrate resistivity of ≦100 m&OHgr;cm and a resistivity of the epitaxial layer of >1 &OHgr;cm without back-surface coating, the epitaxial layer of which semiconductor wafer has a resistance inhomogeneity of <10%.

Abstract: A method for the production of a semiconductor wafer having a front and a back and an epitaxial layer of semiconductor material deposited on the front, includes the following process steps: (a) preparing a substrate wafer having a polished front and a specific thickness; (b) pretreating the front of the substrate wafer in the presence of HCl gas and a silane source at a temperature of from 950 to 1250 degrees Celsius in an epitaxy reactor, the thickness of the substrate wafer remaining substantially unchanged; and (c) depositing the epitaxial layer on the front of the pretreated substrate wafer.

Abstract: A method for the production of a semiconductor wafer having a front and a back and an epitaxial layer of semiconductor material deposited on the front, includes the following process steps:

Abstract: A franking machine for franking mail items has a user interface for operating the franking machine, in particular for inputting and displaying franking parameters and operating steps. In practice, it has often proven to be difficult to operate a franking machine if all texts are displayed in a foreign language. In particular maintenance of a franking machine then also entails serious difficulties. That becomes a problem in particular when the texts in that respect are still displayed in completely foreign characters, for example in the Chinese language. In order to overcome problems of that kind, the franking machine according to the invention has language-switching circuit for switching over the language used in the user interface, which are such that language switching can be effected at any time.