Methods of inspecting wafers for manufacturing light emitting el

Details Methods of inspecting wafers for manufacturing light emitting el Methods of inspecting wafers for manufacturing light emitting el

1993-08-30

1995-08-08

McGraw, Vincent P.

Optics: measuring and testing

Inspection of flaws or impurities

Having predetermined light transmission regions

356239, G01N 2188

Patent

active

054403847

ABSTRACT:
An irradiation light containing a light which wave length is not absorbed by the n-type clad layer, but is absorbed by the p-type active layer, is applied on the wafer for manufacturing light emitting elements with a double-hetero structure of a p-type clad layer, a p-type active layer and an n-type clad layer formed one after another on a semiconductor substrate. Defects are found by detecting the increased photoluminescent light due to generation of a conductivity-type inverted layer such as the n-type inverted layer. When the double-hetero structure is composed of a GaAlAs mixed crystal compound semiconductor, the irradiation light which contains a wavelength range of 600-650 nm is applied. When the defective area is an active layer deficient area, detection is conducted by using the reflection light from the surface of the semiconductor substrate.

REFERENCES:
Tadatomo, et al., "Defects in the active layer p-A10.35Ga0.65As of high-brightness red-light emitting diodes", Semiconductor Science and Technology, vol. 7, No. 1A, Jan. 1992, pp. A98-A103.
Black, J. F., et al., "The use of laser-induced photoluminescence to evaluate GaAsP wafers for red-light emitting diodes", Journal of the Electrochemical Society, vol. 119, No. 3, Mar. 1972, pp. 369-372.

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