Visualization of the depleted layer in nanoscaled pn junctions on Si(011) surfaces with the use of scanning tunneling microscopy

We demonstrate that the microscopic variation of the bulk electronic proper ties of nanoscaled pn junctions formed on Si(001) surface is clearly visual ized with the use of scanning tunneling microscopy/scanning tunneling spect roscopy (STM/STS). The STM measurement reveals that it is possible to disti nguish among the n-type the p-type and the depleted p-type regions. It is s hown that the contrasts between the regions strongly depend on the bias vol tage for the STM measurement. Especially, for the negative sample bias volt age, it is observed that the width of the depletion layer gets wider with d ecreasing the sample bias voltage. We will discuss the origin of the bias v oltage dependence of the STM image in terms of a metal-insulator-semiconduc tor structure model. It is also shown that the current imaging tunneling sp ectroscopy image can also visualize three regions of the nanoscaled pn junc tions. (C) 1999 Elsevier Science B.V. All rights reserved.