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US4128338A
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Modified optical transmission technique for characterizing epitaxial layers
Assignee: Honeywell Inc
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Filing: 1977-06-17
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Granted: 1978-12-05
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Expires: 1997-06-17
Abstract
Abstract An improved method of determining the energy bandgap of an epitaxial semiconductor layer on a substrate corrects for an overestimation of energy gap yielded by normal optical transmittance measurements. The overestimation of energy bandgap is caused by a graded bandgap region which exists between the epitaxial semiconductor layer and the substrate.
Inventors
- 👤 Theodore T. S. Wong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:12
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/26; G01R31/265; G01R31/2656
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
105 words
A method of determining the energy bandgap of an epitaxial semiconductor layer on a substrate, wherein a graded bandgap region exists between the epitaxial semiconductor layer and the substrate, the method comprising: determining the thickness d S of the substrate, the thickness d G of the graded bandgap region, and the thickness d L of the epitaxial semiconductor layer; measuring optical transmittance of the layer, graded bandgap region and substrate as a function of wavelength; and determining the energy gap of the layer from the values of d S , d G , and d L and the results of the measuring of optical transmittance.
Claim 2
Independent Claim
105 words
A method of determining the energy bandgap of an epitaxial semiconductor layer on a substrate, wherein a graded bandgap region exists between the epitaxial semiconductor layer and the substrate, the method comprising: determining the thickness d S of the substrate, the thickness d G of the graded bandgap region, and the thickness d L of the epitaxial semiconductor layer; measuring optical transmittance of the layer, graded bandgap region and substrate as a function of wavelength; and determining the energy gap of the layer from the values of d S , d G , and d L and the results of the measuring of optical transmittance.
Claim 3
Dependent Claim
34 words
The method of claim 1 wherein determining thicknesses d S , d G , and d L is by a destructive testing technique on a portion of the layer, graded bandgap region, and substrate.
Claim 4
Dependent Claim
39 words
The method of claim 2 wherein the destructive testing technique comprises: angle-lapping an edge of the layer to expose a portion the layer, the graded bandgap region, and substrate; and performing electron beam microprobe measurements on the exposed portion.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-12-04 | 1982-06-05 | 1982-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-12-04 | 1986-06-05 | 1986-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-12-04 | 1990-06-05 | 1990-12-05 | $7700.00 | Window Closed / Lapsed |