H. Yamaguchi et Y. Hirayama, IMAGING OF LOCAL CHARGE-DENSITY IN AN INAS GAAS 2-DIMENSIONAL HETEROSTRUCTURE BY SCANNING-TUNNELING-MICROSCOPY/, JPN J A P 2, 37(8A), 1998, pp. 899-901
We have studied the bias-voltage dependence of constant-current images
obtained by scanning tunneling microscopy (STM) at 4.8 K on an InAs t
hin film grown on GaAs (111)A substrates. In-plane surface-height vari
ation as large as 0.1-0.2 nm was detected on the step-free region, onl
y with the negative sample voltages higher than similar to 0.6 V. Beca
use the bias condition corresponds to the tunneling of electrons accum
ulated in the InAs film to the STM tip, we believe that the image refl
ects the local electron density in InAs/GaAs two-dimensional heterostr
uctures.