Atomic scale images of acceptors in III-V semiconductors [Elektronische Ressource] : band bending, tunneling paths and wave functions / Sebastian Loth

his volume reports measurements of single dopant atoms in III-V semi- Sebastian LothTconductors with low temperature scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). It investigates the anisotropic spatial distribution of acceptor induced tunneling processes at the {110} Atomic Scale Images of Acceptors cleavage planes. Two different tunneling processes are identified: conven-tional imaging of the squared acceptor wave function and resonant tunne- in III-V Semiconductorsling at the charged acceptor. A thorough analysis of the tip induced space charge layers identifies characteristic bias windows for each tunnel process. Band Bending, Tunneling Paths The symmetry of the host crystal’s band structure determines the spatial distribution of the tunneling paths for both processes. Symmetry reducing and Wave Functionseffects at the surface are responsible for a pronounced asymmetry of the acceptor contrasts along the principal [001] axis. Uniaxial strain fields due to surface relaxation and spin orbit interaction of the tip induced electric field are discussed on the basis of band structure calculations. High-reso-lution STS studies of acceptor atoms in an operating p-i-n diode confirm that an electric field indeed changes the acceptor contrasts. In conclusion, the anisotropic contrasts of acceptors are created by the host crystal’s band structure and concomitant symmetry reduction effects at the surface.