ECR ION AND FREE-RADICAL SOURCES FOR MBE APPLICATIONS

A small 2.45 GHz ion/free radical source that has been specifically designed for MBE applications is described. The overall outside diameter of this cylindrical source is 5.8 cm (includes magnets and applicator) and the length is less than 15 cm. Thus, it fits through vacuum ports on existing MBE machines and can be placed near the substrate. The microwave discharge, which is created within a cylindrical quartz tube, is surrounded by rare-earth magnets and a tunable coaxial cavity applicator. Single or double accelerating grids can be placed on the 3.75-cm-diam discharge output producing an ion beam, or the discharge can be freely exhausted into the vacuum allowing the charged and excited species to diffuse onto the substrate for plasma and/or free radical processing. This device can operate at pressures as low as 10- 5 Torr with A, O2, and N2 gases using only 50-150 W of incident power. The detailed description and the preliminary experimental test of this source is discussed.