Method and apparatus for determining minority carrier diffusion length in semiconductors

Patent · Tue Jul 12 00:00:00 EDT 1983

OSTI ID:864622

Goldstein, Bernard ^[1]; Dresner, Joseph ^[1]; Szostak, Daniel J ^[2]

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1. Princeton, NJ
2. Mercerville, 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. An unmodulated illumination 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. A vibrating Kelvin method-type probe electrode couples the SPV to a measurement system. The operating optical wavelength of an adjustable monochromator to compensate for the wavelength dependent sensitivity of a photodetector is selected to measure the illumination intensity (photon flux) on the silicon. Measurements of the relative photon flux for a plurality of wavelengths are plotted against the reciprocal of the optical absorption coefficient of the material. A linear plot of the data points is extrapolated to zero intensity. The negative intercept value on the reciprocal optical coefficient axis of the extrapolated linear plot is the diffusion length of the minority carriers.

• DOE Contract Number: XJ-9-8254-1
• Assignee: RCA Corporation (New York, NY)
• Patent Number(s): US 4393348
• Application Number: 06/228,575
• OSTI ID: 864622
• Country of Publication: United States
• Language: English

Related Subjects

method
apparatus
determining
minority
carrier
diffusion
length
semiconductors
provided
carriers
semiconductor
material
particularly
amorphous
silicon
significantly
constant-magnitude
surface-photovoltage
spv
unmodulated
illumination
provides
light
excitation
surface
generate
manually
controlled
automatic
servo
maintains
constant
predetermined
value
vibrating
kelvin
method-type
probe
electrode
couples
measurement
operating
optical
wavelength
adjustable
monochromator
compensate
dependent
sensitivity
photodetector
selected
measure
intensity
photon
flux
measurements
relative
plurality
wavelengths
plotted
reciprocal
absorption
coefficient
linear
plot
data
extrapolated
zero
negative
intercept
axis
carrier diffusion
optical wavelength
optical absorption
diffusion length
amorphous silicon
semiconductor material
minority carrier
predetermined value
absorption coefficient
photon flux
minority carriers
automatic servo
manually controlled
particularly amorphous
optical wave
modulated illumination
determining minority
constant predetermined
light excitation
wavelength dependent
reciprocal optical
magnitude surface-photovoltage
/324/136/