Characterization of and detection of defects in semiconductor crystals by infrared light scattering tomography

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Defects in crystals, such as dislocations, stacking faults, segregated impurities and interstitial atoms, will induce scattered light with disordered phases according to their disordered positions, because all atoms radiate from their dipoles generated by illumination of a laser beam.Since electrical characteristics of GaAs crystals is strongly dependent upon EL2 centers, their density and distribution must be controlled and adjusted for opto-electric and high electron mobility devices, where infrared light scattering tomography (IR-LST) is very useful for these processing because the centers are clearly observed by IR-LST.Dispersions of the absorption and scattering due to EL2 centers are caused by resonance of electrons trapped in the EL2 centers.Since ZnSe crystal is one of the most promising candidates for blue lasers, detection of defects in and characterization of the crystals are successfully done by LST and Raman scattering tomography (RST). Here, a new habit of dislocations wa … More s observed by LST : many dislocations were piled up within thin layrs on (111) planes of the crystals, which are called "DISLOCATION WALLS".Density and distribution of intrinsic gettering (IG) centers and quality of denuded zones in Cz-Si wafers are very important for planar devices on wafer surfaces because a sigle crystalline layr is epitaaxially grown on the denuded zone, which is, therefore, the most important key factors.The defects located just under a mirror polished surface are very harmful for the epitaxial growth, even if they were very tiny and few. Here we have developed an inside total reflection (ITR) method to clearly and accurately detect the defects and interstitial oxygen atoms there, because only the light scattered by the defects and interstitial atoms can pass through the mirror surface since this light impinges ontothe surface with angles smaller than the total reflection angle while the total reflection prevents the main part of the laser beam from passing through. Less