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High Spatial Resolution Measurement of Doping, Band-Bending, And Recombination at Semiconductor Surfaces

IP.com Disclosure Number: IPCOM000100974D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Hamers, R: AUTHOR [+2]

Abstract

This article proposes a way of measuring surface dopant profiles, local band-bending, and recombination rates at semiconductor surfaces and interfaces with a spatial resolution as small as 10 Ao, based on the use of a scanning tunneling microscope to measure the local photoelectric voltage ("photovoltage") or photoelectric current ("photocurrent") generated upon optical illumination.

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High Spatial Resolution Measurement of Doping, Band-Bending, And Recombination at Semiconductor Surfaces

       This article proposes a way of measuring surface dopant
profiles, local band-bending, and recombination rates at
semiconductor surfaces and interfaces with a spatial resolution as
small as 10 Ao, based on the use of a scanning tunneling microscope
to measure the local photoelectric voltage ("photovoltage") or
photoelectric current ("photocurrent") generated upon optical
illumination.

      In the near surface region of a semiconductor, the valence and
conduction bands are shifted with respect to their energies in the
bulk, due to the presence of surface and interface states.  In the
case of silicon, the bands bend such that the Fermi level at the
surface lies nearly midway between the valence and conduction bands.
Illumination with light having an energy greater than the bulk
bandgap generates electron-hole pairs in the near-surface region
which, because of the band-bending, then result in a photoelectric
voltage (SPV) at the surface. This voltage will be positive if the
doping near the surface is n-type and will be negative if the doping
is p-type.  As the illumination intensity is increased, the surface
photovoltage will saturate at the flat-band voltage.
      The primary ideas behind this invention are:
      1) Illumination of a semiconductor surface or interface with
light having an energy greater than the bulk band-gap.  This
intensit...