Interplay between tip-induced band bending and voltage-dependent surface corrugation on GaAs(110) surfaces

Abstract

Atomically resolved, voltage-dependent scanning tunneling microscopy ͑STM͒ images of GaAs͑110͒ are compared to the results of a one-dimensional model used to calculate the amount of tip-induced band bending for a tunneling junction between a metal and a semiconductor. The voltage-dependent changes in the morphology of the atomic lattice are caused by the four surface states of the GaAs͑110͒ surface contributing in varying relative amounts to the total tunneling current. Tip-induced band bending determines which of these states contributes to the total tunneling current at a given bias voltage, and thus has a profound influence on the voltage-dependent STM-images. It is shown that certain voltage regions exist, for which none of the surface states present at the GaAs͑110͒ surface can contribute to the tunneling current. For these voltages, tunneling occurs between the tip and bulk states of the sample through a surface depletion layer several nm wide. Nevertheless, we observe atomic, surface like corrugation for these circumstances.

Spatially resolved electronic structure of an isovalent nitrogen center in GaAs

“…The A4 and A5 states are centered around the arsenic surface atoms and are both directed along [110]. As was reported by de Raad et al [58], due to TIBB it is possible to observe contributions from the C3 mode also at negative voltages when tunneling close to the gap. Therefore, at −1.90 V a 2D grid is formed from the C3 state and the A5 state, whose maximum is located closer to the gap than that of the A4.…”

Light emission induced by tunneling electrons from surface nanostructures observed by novel conductive and transparent probes

“…Figure 5a and b show an STM topography image and an STM-luminescence map obtained simultaneously on the p-GaAs(110) surface. The protrusions appearing on the STM topography image correspond to the Zn dopants located at the sub-surface layers (de Raad et al, 2001;Zheng et al, 1994). The apparent height of the protrusions is related to the depth of the Zn dopants in the sub-surface layers.…”

Band structure related wave-function symmetry of amphoteric Si dopants in GaAs

“…The TIBB is negative, the conduction band is pulled under the Fermi energy and electrons are accumulated. The atomic corrugation of the delocalized conductivity resembles the C3 surface resonance in the conduction band [23]. This indicates that the imaged conductivity is at the conduction band.…”

“…Both topographies are acquired at −1.8 V. The conduction band is pulled under the Fermi energy. Electrons are accumulated at the surface and the C3 surface resonance is detected above the undisturbed surface (seen as lines running along the [001] direction) [25,23]. The donor (Fig.…”

“…Based on the experimental determination of the tip work function [18] (4.3 eV in the presented STS-measurement) the flat band bias is fixed to −0.2 V bias. The complete TIBB(V) dependence is then numerically evaluated [20,23,24].…”