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Article type: Cover
1986 Volume 13 Issue 2-3 Pages
Cover1-
Published: October 15, 1986
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Article type: Appendix
1986 Volume 13 Issue 2-3 Pages
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Article type: Index
1986 Volume 13 Issue 2-3 Pages
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Article type: Index
1986 Volume 13 Issue 2-3 Pages
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Article type: Index
1986 Volume 13 Issue 2-3 Pages
121-
Published: October 15, 1986
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Takao Abe, Hirofumi Harada
Article type: Article
1986 Volume 13 Issue 2-3 Pages
122-130
Published: October 15, 1986
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Unintentionally and highly doped impurities in semiconductor silicon crystals are the light elements such as carbon, nitrogen and oxygen, which are typically contained with 〜1x10_16 atoms/cm^3,<2x10^14 atoms/cm^3 (detection limit) and 〜1x10_18 atoms/cm^3, respectively. More precise control of these light element concentrations in silicon wafers will be required for the future LSI fabrications. Incorporation mechanisms of these elements into crystals during growth including the values of segregation coefficients are described which have very different properties from the III and V elements. The characteristics of these elements are as follows: 1. Carbon: There are many sources of CO gas in CZ furnaces and its introduction into the melt will be influenced by the equilibrium reaction of {C} + {O}⇔CO. { } means chemical species in the melt. It seems that carbon is incorporated into crystal as SiC. Because of SiC impurity, carbon has a small equilibrium segregation coefficient. Carbon in crystal enhances the excess vacancy concentration during growth like as boron.
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Masashi Kumagawa, Yasuhiro Hayakawa
Article type: Article
1986 Volume 13 Issue 2-3 Pages
131-135
Published: October 15, 1986
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GaSb single crystals containing Te as an impurity were pulled from the melt by the Czochralski method. Microfacets concerning with local segregation phenomena were investigated in these crystals. They appeared when deep holes on irregular crystal surfaces caused by remelting were filled in with bulk material during regrowth. Furthermore, line patterns showing a sawtoothed shape were observed in the transition region between peripheral facet and off-facet regions. They were formed with {111} facet planes. A macrofacet region developed from a microfacet was also found in pulled crystals.
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Tatau Nishinaga, Kangsa Pak, Chiaki Sasaoka
Article type: Article
1986 Volume 13 Issue 2-3 Pages
136-143
Published: October 15, 1986
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The behavior of LPE macrostep during the growth was studied by using photoluminescence image and spatially resolved photoluminescence taking GaP doped with zinc, oxygen and nitrogen as examples. It was shown that the impurities were doped much more heavily on the macrostep terrace than on the riser. To understand the impurity inhomogeneity around the macrostep, the interface supersaturation was calculated theoretically around the macrostep by using conformal mapping. The calculation showed that the interfacial supersaturation was very small such as 0.01% and this led to the conclusion that the rejection of the impurity from the growing crystal occurs not at the kink or on the surface of the growth step but at the edge of the step.
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Shintaro Miyazawa
Article type: Article
1986 Volume 13 Issue 2-3 Pages
144-150
Published: October 15, 1986
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Dislocations in LEC-grown, semi-insulating GaAs are not only contibutable to variations of material parameters, but tonon-uniformity of FET performances. The paper highlights current understandings in relationship between dislocations and FET threshold voltage, and then discusses a close correlation between dislocations, native defects AsGa antisites and threshold voltage by means of defect reaction equilibrium around dislocations. Finally, a local segregation of point defects (local inhomogeneities) around dislocations is presented so as to explain overall the effects of point defects on device properties
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Shoichi Ozawa, Tsuguo Fukuda
Article type: Article
1986 Volume 13 Issue 2-3 Pages
151-158
Published: October 15, 1986
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Effects of magnetic field on impurities and native defects distributions were investigated in detail in conjunction with the strengths of applied magnetic field. It was found that inhomogeneities of local impurity distribution caused by irregular striations and periodic striations were remarkably suppressed in the presence of magnetic field about 3000 Gauss during growth. It was confirmed that effective segregation coefficients of carbon and indium in GaAs approach unity as the magnetic field increases. Although the midgap deep donor EL2 concentrations only varied from 1 to 4 X 10^<16>cm^<-3> in the conventional LEC GaAs crystals, they ranged from far below 1 X 10^<15>cm^<-3> in Ga-rich melt to 1 X 10^<17>cm^<-3> in As-rich melt for the magnetic field applied LEC ( MLEC ) GaAs crystals. Segregation phenomena of EL2 were found to vary with the arsenic mol fraction in the melt in MLEC crystals. The homogeneity of the native defect and impurity distributions in MLEC crystals was far superior to that of LEC crystals, which resulted in homogeneous semi-insulating property of MLEC GaAs crystals. Based on these results, we have proposed a programmed magnetic field applied LEC crystal growth technique and demonstrated the controllability of the impurity distribution along the growth axis by this technique.
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[in Japanese]
Article type: Article
1986 Volume 13 Issue 2-3 Pages
158-
Published: October 15, 1986
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Junji Matsui, Tomohisa Kitano, Haruhiko Ono, Tetsuya Ishikawa
Article type: Article
1986 Volume 13 Issue 2-3 Pages
159-165
Published: October 15, 1986
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Strain distribution in (001) LEC-grown GaAs wafers was investigated mainly by means of X-ray reflection topography. Local strain fields were observed around <100> radii with fourfold symmetry for high dislocation density wafers and between <100> and <110> radii with eight-fold symmetry for low dislocation density wafers. The latter can be explained by taking Schmid factor destribution under a tangential stress being exerted along water periphery into account. Major dislocations contributing to the strain distnbution and dislocatron multiplication are thought to be screw ones.
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Naohisa Inoue, Kazumi Wada
Article type: Article
1986 Volume 13 Issue 2-3 Pages
166-172
Published: October 15, 1986
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Recent works on oxygen precipitation in Czochralski. silicon are summarized. These include studies on oxide precipitate growth, precipitate formation during cooling after crystal growth, and steady state as well as nonsteady state nucleation during annealing. It was found that the oxide precipitate growth is limited by the oxygen diffusion. We demonstrate that the homogeneous nucleation is the dominant process in the oxygen precipitation in carbonlean crystals. Time-lag in nucleation in high-low temperature two step annealing is briefly discussed On these bases, precise control of precipitate density and size is established. It is emphasized that the oxygen in silicon is the most interesting system in the nucleation research area.
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Hisaaki Suga
Article type: Article
1986 Volume 13 Issue 2-3 Pages
173-179
Published: October 15, 1986
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Segregation characteristics of impurities to deliberately introduced crystal defects in Si has been well utilized against an unexpected contamination during IC device fabrication processes. Present paper shows the experimental results of direct observation of impurity gettering for various metal species under oxidizing ambient. These results were mostly obtained by using the secondary ion mass spectrometer and the analytical electron microscopy. Such elements as Fe, Cr, In, Mo, Ta and Al which have the strong affinity with oxygen were almost immobile and remained at the wafer surface. On the other hand, such elements as Cu, Au and Ni with the relatively weak affinity with oxygen could diffuse to the defective region away from the electrical active surface.
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Osamu Ueda, Satoshi Komiya
Article type: Article
1986 Volume 13 Issue 2-3 Pages
180-188
Published: October 15, 1986
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Transmission electron microscopy and related techniques are applied to the investigation of various defects in semiconductors induced by local segregation during crystal growth, device fabrication process, and operation of devices. Structure and nature of defects in heavily doped liquid phase epitaxial crystals of GaAlAs/GaAs, InGaAsP/InP, and InGaAsP/GaAs are investigated and compared in terms of point defect reaction during crystal growth. Composition-modulated structures are observed in InGaAsP crystals due to spinodal decomposition of the crystal during the growth process. Intrinsic gettering centers in oxygen-free silicon crystals during standard three step annealing process are identified. The gettering centers correspond to butterfly-type defect complexes consisting of dislocation loops and microprecipitates. Supersaturation of silicon interstitials is resposible for this process. Defect structures in gradually degraded GaAlAs and InGaAsP/InP double-heterostructure light emitting diodes are investigated structurally and compared regarding recombination enhanced defect reaction during operation. In each study, it is particularly emphasized that these structural and compositional techniques are extremely effective for the identification of defects in semiconductor materials and devices induced by local segregation.
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Jimpei Harada, Yasuharu Kashihara
Article type: Article
1986 Volume 13 Issue 2-3 Pages
189-195
Published: October 15, 1986
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The observation of diffuse scattering due to short-range order ( SRO) between Al and Ga atoms in (Al_0.5 Ga_0.5)As which were grown by molecular beam epitaxy, has been made using both electron and X-ray diffraction methods. Only diffuse streaks along the <110> direction were detected, the origin of which must be low frequency transverse acoustic phonons. The absence of SRO diffuse scattering is considered as an evidence of random distribution of Al and Ga atoms in this substance, consistent with the thermodynamical calculation by Onabe ( K. Onabe: Jpn. J. Appl. Phys. 21 (1982) L323).
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Shoji Kuma, Yoohei Otoki
Article type: Article
1986 Volume 13 Issue 2-3 Pages
196-201
Published: October 15, 1986
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Recently, the infrared light scattering tomography has been noticed as an observation method of defects in crystals. The tomography detects the difference of the optical properties around defects caused by crystal inperfection using the advanced technique of image processing by laser and computer. The system is easily joined with the other optical imaging systems such as EL2 distribution imaging by infrared light absorption, etc. In this paper, several interesting application of the infrared light scattering tomography on GaAs crystals have been introduced: (1) The scattering images agree well with dislocations. This result has lead us to develop new methods of stereographic observation of dislocations. (2) The images have been compared to the EL2 distribution measured by the infrared absorption on the samples before and after annealing. (3) On the In doped GaAs crystals, the disagreement between the scattering tomography and X-ray topograph has been found, which suggests the constitutional super cooling of high In content in the growth.
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Takashi Katoda
Article type: Article
1986 Volume 13 Issue 2-3 Pages
202-208
Published: October 15, 1986
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An application of laser Raman spectroscopy to estimate the clustering parameters and internal stress accumulated in each bond in Ga_0.5Al_0.5As, Gao_0.52In_0.48P, Ga_<1-χ>In_χAs (0≦χ≦0.53), and GaAs_0.7P_0.3 is proposed. The clustering parameters and stress are evaluated from the phonon intensity and the difference between the observed optical phonon frequencies and those calculated in terms of the modified REI model respectively. The estimated values of the clustering parameter agree fairly well with those obtained from theoretical calculation of the excess free energy of mixing. The bond lengths in Ga<1-χ>In_χAs (0≦χ≦0.53) are derived from the stress, and are compared with published data on extended X-ray absorption fine structure.
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[in Japanese], [in Japanese]
Article type: Article
1986 Volume 13 Issue 2-3 Pages
209-
Published: October 15, 1986
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Article type: Appendix
1986 Volume 13 Issue 2-3 Pages
210-
Published: October 15, 1986
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Article type: Appendix
1986 Volume 13 Issue 2-3 Pages
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Published: October 15, 1986
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Article type: Cover
1986 Volume 13 Issue 2-3 Pages
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Published: October 15, 1986
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