ION BEAM DEPOSITION OF INFRARED SENSITIVE AMORPHOUS ALLOY FILMS
Original Publication Date: 1987-Oct-31
Included in the Prior Art Database: 2004-Apr-04
Xerox Disclosure Journal
US. Patents 4,376,688 and 4,416,755 describe methods for producing semiconducting films and in particular hydrogenated amorphous silicon films for use in xerographic photoreceptor applications by generating a plasma of reactive gas, extracting, accelerating and directing an ion beam from the plasma toward a target of the material of which the film is to be formed which is maintained in a vacuum chamber thereby sputtering the target material with the reactive ion beam and collecting the sputtered target material as a film on the substrate. With such a process, it is possible to more closely and precisely control the deposition process. For certain photoreceptor applications such as in xerographic laser printers, it is desirable to use a photoreceptor that is sensitive to the near infrared light emitted by solid state diode lasers such as gallium arsenic lasers which enable the use of simplified light modulation systems as well as reducing both the cost and size of the printer light source. This may be achieved by preparing infrared sensitive a- SiGe:H alloys while utilizing the ion beam deposition process and a target consisting of either a silicon germanium alloy, or a collage of silicon and germanium. Figures la, lb and lc illustrate alternative examples of target structures that can be used. Figure la is a homogeneous polycrystalline target of silicon and germanium alloy. Figure lb is a pie-slice assembly of silicon and germanium and Figure lc is a checkerboard assembly of germanium on silicon. Targets lb and lc can be fabricated from single crystal germanium wafers overlayed onto a silicon target with adhesives that are stable in a sputtering environment. Furthermore, with these targets, the silicon/germanium ratio can be readily altered to produce any alloy composition and some of the patched segments could be predoped to produce doped films.