Method and apparatus for determining minority carrier diffusion length in semiconductors

Patent · Tue Jun 12 04:00:00 EDT 1984

OSTI ID:5755287

Moore, A R

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 drop of a transparent 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 drop of redox couple solution functions to create a liquid Schottky barrier at the surface of the material. Illumination light is passed through a transparent rod supported over the surface and through the drop of transparent electrolyte. The drop is held in the gap between the rod and the surface. Steady red light is also used as an optical bias to reduce deleterious space-charge effects that occur in amorphous silicon.

• Assignee: RCA Corporation
• Patent Number(s): US 4454472
• OSTI ID: 5755287
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420800* -- Engineering-- Electronic Circuits & Devices-- (-1989)
CHARGE CARRIERS
CHEMICAL REACTIONS
DIFFUSION LENGTH
DIMENSIONS
ELECTROLYTES
ELEMENTS
LENGTH
MATERIALS
MEASURING METHODS
PHOTOELECTRIC EFFECT
PHOTOELECTROMAGNETIC EFFECTS
REDOX REACTIONS
SCHOTTKY EFFECT
SEMICONDUCTOR MATERIALS
SEMIMETALS
SILICON