Compositional mapping of semiconductor structures by friction force microscopy

Topographic and chemical mapping of materials at high resolution define the goals of a microscope. Force microscopy can provide methods for simultaneous topography and chemical characterization of materials. Here we describe the use of the atomic force microscope to map chemical variations of semiconductor samples. Chemical maps of semiconductor InP/InGaAs alloys have been determined with 3 nm spatial resolution while 10% changes in indium composition are resolved in InxGa1−xAs structures. The present resolution is limited by the tip’s curvature radius, cantilever lateral force constant, and the total applied force. Theoretical calculations predict lateral compositional resolutions of about 1 nm.