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  • Cambridge University Press (CUP)  (4)
  • 1990-1994  (4)
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  • Cambridge University Press (CUP)  (4)
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  • 1990-1994  (4)
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  • 1
    Online Resource
    Online Resource
    Superhigh-Resolution Structural Image of InP Along [110] Zone Axis
    Cambridge University Press (CUP) ; 1990
    In:  Proceedings, annual meeting, Electron Microscopy Society of America Vol. 48, No. 1 ( 1990-08-12), p. 80-81
    Details
    In: Proceedings, annual meeting, Electron Microscopy Society of America, Cambridge University Press (CUP), Vol. 48, No. 1 ( 1990-08-12), p. 80-81
    Abstract: During the past decade , K.IZUI and S.FURUNO [1] reported the structural image of Si along [110] direction with the bright spots representing the columns of atoms. This result remain somewhat controversial. J.L.HUTCHISON and W.G.WADDINGTON [2] elucidated the image as the lattice image, not the structural image , for the computer simulation showed that this just is the artifice due to electron optics. Mallard et.al [3] reported HREM image of GaInAs/InP interface along [110] direction and consider that it is not a true structure image because the spots in pairs on the picture were not representative of accurate atomic positions. Here we report the superhigh resolution image of InP along [110] direction. Combining with computer simulation technique, it is confirmed that the observed image is the structural image of InP along [110] direction. The black spots represent to the atomic columns. The nearest distance of In and P is 1.47Å as shown in the picture, which is smaller than the point-point resolution 1.9Å of JEOL-4000EX electromicroscope. Fig.1 is the superhigh resolution image of InP along [110] direction. The thickness of the specimen is about 350Å, and defocus is about ΔF=-470Å. The bigger bright spots correspond to the atomic channels. The different size black spots represent the columns of In and P atoms.Fig.2 shows the simulated structural image of InP along [110] direction obtained by multi-slice method. Fig.3 show that the thickness of the specimen depends on the amplitude of electron waves. When the amplitudes of transmitted beams reach nadirs and the amplitudes of diffracted 111, 002,220,004 beams are relatively strong, the contrast of the structural image is better. It is indicated that the amplitudes of transmitted beam interacts with diffracted beams according to the dynamical theory of electron diffraction and the electron waves passing through the sample have nearly the same amplitude, so that both In and P atomic columns may imaged. These results are in good agreement with the results on another paper about the explanation of structural image of InP along [001] direction[4]. The phases of the electron waves were investigated as shown in Fig.4. The transmitted beam has, the same value of phases as diffraced beams at the thickness of 350Å. This work is very similar to that of Au atomic image along [110] direction reported by prof. H.Hashimoto.[5] It is considered that the atomic images can be formed when obseved specimen is rather thin or near optimum thickness at which the phase of the image-forming waves the same values. This is very important for the explanation of the superhigh resolution image. The curve of CTF of JEOL--4000ex operated at 400kv with different defocuses were calculated. The CTF of sherzer condition is ΔF=-406Å. In our experiment, the superhigh resolution structural images were obtained with ΔF=-465Å, which is close to the scherzer condition. It is obvious that the electron beams with lower indexes were nearly included in the plateau of CTF curve where sinx ≈ 1, as shown in Fig.5, which may carries a lot of information about the structure, thus the atomic images of InP can be formed.
    Type of Medium: Online Resource
    ISSN: 0424-8201 , 2690-1315
    URL: Article
    DOI: 10.1017/S0424820100179154
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1990
    SSG: 11
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Accuracy of Stereoscopic Technique in S.E.M.
    Cambridge University Press (CUP) ; 1990
    In:  Proceedings, annual meeting, Electron Microscopy Society of America Vol. 48, No. 1 ( 1990-08-12), p. 416-417
    Details
    In: Proceedings, annual meeting, Electron Microscopy Society of America, Cambridge University Press (CUP), Vol. 48, No. 1 ( 1990-08-12), p. 416-417
    Abstract: The principle of 3-D reconstrution for SEM image is not so conplex, ie. the SEM image of polar project is treated with a rectangular coordinate, however,it accuracy is an attractatble topic.The accuracy of a stereopair is effected by following factors: (1) Sample's position: Image’s field depth of SEM is determined by
    Type of Medium: Online Resource
    ISSN: 0424-8201 , 2690-1315
    URL: Article
    DOI: 10.1017/S0424820100180835
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1990
    SSG: 11
    Location Call Number Limitation Availability
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Accuracy of Stereoscopic Technique in S.E.M.
    Cambridge University Press (CUP) ; 1990
    In:  Proceedings, annual meeting, Electron Microscopy Society of America Vol. 48, No. 1 ( 1990-08-12), p. 598-599
    Details
    In: Proceedings, annual meeting, Electron Microscopy Society of America, Cambridge University Press (CUP), Vol. 48, No. 1 ( 1990-08-12), p. 598-599
    Abstract: The principle of 3-D reconstrution for SEM image is not so conplex, ie. the SEM image of polar project is treated with a rectangular coordinate, however, it accuracy is an attractatble topic. The accuracy of a stereopair is effected by following factors: (1) Sample’s position: Image’s field depth of SEM is determined by where, F 4 : the depth of field D 0 : resolution of image β : condence angle of E-beam (about 1 × 10 −3 rad.) when the magnificaton is 1000 times, ie. D o = 0.1μm, then F f = 100μm. To get an accurate stereopair, one should keep the interested points on the specimen in the same field depth before and after tilting operation. During the operation, a point displacement is sketched in Fig.1, where 0 is tilting axis. A o is the original position of A, A, is tilted one, α is tilted angle and β is the angle betweem 0A o and Z axis. After the tilt, the perpendicular displacement of A point is and the horizontal one is Generally, the magnification is 1000X, ie. F f =100μm, α≈10°, if β 〈 =30° then, 0A o 〈 =700μm is the condition for that Z A 〈 = 100 m.
    Type of Medium: Online Resource
    ISSN: 0424-8201 , 2690-1315
    URL: Article
    DOI: 10.1017/S0424820100181750
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1990
    SSG: 11
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    Online Resource
  • 4
    Online Resource
    Online Resource
    Hrem Study of Extended Dislocation in InP
    Cambridge University Press (CUP) ; 1990
    In:  Proceedings, annual meeting, Electron Microscopy Society of America Vol. 48, No. 1 ( 1990-08-12), p. 596-597
    Details
    In: Proceedings, annual meeting, Electron Microscopy Society of America, Cambridge University Press (CUP), Vol. 48, No. 1 ( 1990-08-12), p. 596-597
    Abstract: We observed the HREM images of extended dislocations in InP crystals and the effects of electoron beam on their configurations. InP crystals were grown by LEC method. The samples used for HREM observation were prepared by crushing technique. The observation was performed using a 4000EX HREM at 400KV with beam current density 10Pa/cm 2 and magnification 8×10. 5 The direction of observation is parallel to [110] zone axis of the specimen. It was found that there were a number of extended dislocations in InP crystal. They consist of two partial dislocations with Burgers vectors of 1/6[211] and l/6[121] and an piece of intrinsic stacking fault between them. Fig. 1. shows an extended dislocation observed. The contrast changes induced by the stress field of partial dislocations and the relative displacement of the lattice on the two sides of the stacking fault should be noted. The measurement show that the average width of extended dislocations in Inp crystal is about 155Å. The stacking fault energy estimated by the average width is about 170 ergs/cm 2 . Observation found that the extended dislocations might movei contract or further extend its width due to the electron beam irradiation during the HREM observation. Fig. 1. to 4. are the successive photographs of the same area. The interval between the two successive pictures is about 10 sec. The extended dislocation contracted continuously so that it became a nearly perfect dislocation with Burgers vector b=1/2[110l in Fig.4. It is obvious that the higher thermal stress induced by beam irradiation may produce the motion as well as the width changes of extended dislocations in InP crystal.
    Type of Medium: Online Resource
    ISSN: 0424-8201 , 2690-1315
    URL: Article
    DOI: 10.1017/S0424820100181749
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1990
    SSG: 11
    Location Call Number Limitation Availability
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    Online Resource
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