Correlative SEM/STM study of local electronic properties in compound semiconductors

Abstract

The use of combined SEM/STM instruments enables to position the tunnel tip in the region of the sample to be investigated by STM or/and by scanning tunneling spectroscopy (STS). In this work a STM has been implemented in the chamber of a SEM provided with EBIC and CL detection systems. With this arrangement, correlative STM and SEM-EBIC or SEM-CL measurements of local electronic properties have been performed in different compound semiconductors as CdTe, CdxHg1-xTe, GaSb or ZnO. In particular, the electronic inhomogeneities of the sample were analyzed with nm resolution by current imaging tunneling spectroscopy (CITS) or using STM-REBIC contacts configuration, in areas with different recombination properties as imaged by the SEM beam injection techniques. CITS revealed local variations of the surface band gap in the defect or precipitate-rich areas, observed by EBIC and CL, and appears as a complementary technique to study local electronic properties at a finer scale than the SEM-based techniques.