Low-temperature scanning tunneling spectroscopy as a probe for a confined electron gas
4.Physikalisches Institut - Bunsenstraße 13, D-37073
Accepted: 22 December 1998
In situ cleaved (110) surfaces of n-doped GaAs have been investigated by scanning tunneling microscopy (STM) and spectroscopy (STS) at temperatures from 8 K to 300 K. At low temperatures oscillatory features in the topography around individual donor atoms embedded in the GaAs matrix and peaks in the differential conductivity curves are seen. Both vanish with increasing temperature. The experimental results are described consistently in the framework of quantized subbands of a low-dimensional electron gas within the band-bending region which is induced by the STM tip. The quantization occurs at unpinned semiconductors surfaces and is also relevant for a quantitative understanding of STM data at room temperature.
PACS: 61.16.Ch – Scanning probe microscopy: scanning tunneling, atomic force, scanning optical, magnetic force, etc / 73.20.Dx – Electron states in low-dimensional structures (superlattices, quantum well structures and multilayers) / 71.55.Eq – III-V semiconductors
© EDP Sciences, 1999