Comments on the appearance of ''mirror'' peaks in mobility spectrum analysis of semiconducting devices

The characterization of semiconductor heterostructures from their mobility spectra has originally been proposed, some 12 years ago, as an improvement of Hall effect measurements. However, the application is far from being tri vial anti often leads to the occurrence of extra peaks without any physical interpretation. They are generally referred to as "mirror peaks" and are i nterpreted in terms of computational artifacts. The present paper comments upon such peaks from a set of data concerning va n der Pauw test structures. Our main conclusion is that from an experimenta l point of view, the transverse component (rho(xy)) of the resistivity tens or is more precisely determined than the longitudinal one (rho(xx)). Thus, we are left with the possibility of artifacts within the experimental proce dure. Starting from an adjustment of all available information (rho(xx) and rho(x y)), a preferential adjustment of rho(xy) leads to the disappearance of "mi rror peaks". As a matter of example, we report the study of an InP-based bi layered structure and show how the mobility spectrum evidences the highly c onducting channel of a HEMT device. (C) 2000 Elsevier Science B.V. All righ ts reserved.