Method and apparatus for determining minority carrier diffusion length in semiconductors

Patent · Mon Feb 20 23:00:00 EST 1984

OSTI ID:864900

Moore, Arnold R ^[1]

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1. Princeton, NJ

Method and apparatus are provided for determining the diffusion length of minority carriers in semiconductor material, particularly amorphous silicon, which has a significantly small minority carrier diffusion length using the constant magnitude surface-photovoltage (SPV) method. Steady or modulated illumination at several wavelengths provides the light excitation on the surface of the material to generate the SPV. A manually controlled or automatic servo system maintains a constant predetermined value of the SPV for each wavelength. A probe electrode immersed in an electrolyte solution containing redox couples (preferably quinhydrone) having an oxidation-reduction potential (E) in the order of +0.6 to -1.65 volts couples the SPV to a measurement system. The redox couple solution functions to create a liquid Schottky barrier at the surface of the material. The Schottky barrier is contacted by merely placing the probe in the solution. The redox solution is placed over and in contact with the material to be tested and light is passed through the solution to generate the SPV. To compensate for colored redox solutions a portion of the redox solution not over the material is also illuminated for determining the color compensated light intensity. Steady red light is also used as an optical bias to reduce deleterious space-charge effects that occur in amorphous silicon.

• Assignee: RCA Corporation (New York, NY)
• Patent Number(s): US 4433288
• Application Number: 06/280,918
• OSTI ID: 864900
• Country of Publication: United States
• Language: English

Related Subjects

-1
/324/136/
65
amorphous
amorphous silicon
apparatus
automatic
automatic servo
barrier
bias
carrier
carrier diffusion
carriers
color
colored
compensate
compensated
constant
constant predetermined
contact
contacted
containing
controlled
couple
couples
create
deleterious
determining
determining minority
diffusion
diffusion length
effects
electrode
electrolyte
electrolyte solution
excitation
functions
generate
illuminated
illumination
immersed
intensity
length
light
light excitation
light intensity
liquid
magnitude
magnitude surface-photovoltage
maintains
manually
manually controlled
material
measurement
merely
method
minority
minority carrier
minority carriers
modulated
modulated illumination
occur
optical
oxidation-reduction
oxidation-reduction potential
particularly
particularly amorphous
passed
placed
placing
portion
potential
predetermined
predetermined value
preferably
probe
provided
provides
quinhydrone
redox
redox couple
redox couples
reduce
reduce deleterious
reduction potential
schottky
schottky barrier
semiconductor
semiconductor material
semiconductors
servo
significantly
silicon
solution
solution containing
solutions
space-charge
spv
steady
surface
surface-photovoltage
tested
value
volts
wavelength
wavelengths