Non-destructively measuring local carrier concentration and gap energy in a semiconductor
US4953983A · kind A · utility
Inventors
Key dates
| Filing date | Mar 25, 1988 |
| Grant date | Sep 4, 1990 |
| Priority date | — |
| Expiry date | Mar 25, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/9501
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus and method for non-destructive measuring of local carrier concentration and bandgap in a semiconductor such as gallium arsenide or gallium aluminum arsenide. A high energy source of photons, e.g. a laser, photo injects carriers on the surface of the semiconductor causing a change in the semiconductor's surface photo reflectance. The fractional change in photo reflectance is measured for a plurality of the photon energies sufficient to identify several Franz-Keldysh peaks, and the photon energies corresponding to these peaks. This information is used to infer the local electric field strength and carrier concentration of the semiconductor as well as semiconductor's bandgap. By noting variations in these parameters throughout the bulk semiconductor, one can identify fatal fabrication flaws in the semiconductor crystal before time and money is expended to fabricate complicated semiconductor architectures in the crystal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.