Loth, S.S.LothWenderoth, MartinMartinWenderothWinking, L.L.WinkingUlbrich, Rainer G.Rainer G.UlbrichMalzer, S.S.MalzerDohler, G. H.G. H.Dohler2018-11-072018-11-072006https://resolver.sub.uni-goettingen.de/purl?gro-2/40346Scanning tunneling spectroscopy (STS) at 8 K is used to study single shallow acceptors embedded near {110}-surfaces ill gallium arsenide (GaAs). At appropriate bias voltages the circularly symmetric contrast normally observed for charged defects evolves into a pronounced triangular shaped protrusion. Comparing dopants at different depths under the surface, we find a linear shift of the associated conductivity maximum along (112) directions. Comparative Studies of Carbon and Zinc acceptors in a modulation-doped heterostructure reveal that both dopants act similarly. The experimental findings Suggest that the highly anisotropic features induced by acceptors resemble a bulk property of the GaAs crystal prominently demonstrating its Ziricblende symmetry.conference_paper10.1143/JJAP.45.2193000236624100073