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The dynamic activities of dislocations and the mechanical properties of various III-V compound semiconductors with a sphalerite structure are reviewed, including current results. Macroscopic stress-strain characteristics and yield strength are described quantitatively in terms of dislocation dynamics on the basis of knowledge of the dynamic behaviour of individual dislocations in these compounds. Various impurities in the compounds affect the mechanical strength through two kinds of effects on individual dislocations: one is the modification of dislocation mobility in glide motion and the other is the immobilization of dislocations. The velocities of rate controlling dislocations during deformation are deduced from analysis of the dynamic state of dislocations.

First results are presented of a study on the impact of O and Ge doping on {113}‐defect formation in Si using in situ2 MeV e‐irradiation in a high voltage electron microscope. Comparison with undoped Si, reveals a suppression of {113}‐defect formation due to O and Ge. The observations are discussed in the frame of a theoretical model assuming quasi‐chemical reactions to describe the intrinsic point defect behaviour during irradiation as a function of irradiation temperature and specimen thickness. It is shown that for irradiations at high temperatures, intrinsic point defect diffusivity values derived from crystal growth and metal diffusion experiments can be used to explain the observations semi‐quantitatively.

The atomistic structure of Czochralski-grown SixGe1-x binary mixed semiconductor was studied experimentally and theoretically. By extended X-ray absorption fine structure (XAFS) studies it was found that bulk SiGe semiconductor is a random mixture and that the Ge-Ge, Ge-Si and Si-Si bond lengths maintain distinctly different lengths and vary in a linear fashion against the alloy composition across the whole composition range 0 < x < 1, in good agreement with expectations derived from the ab-inito electronic structure calculations. The result indicates that SiGe is a suitable model for a disorder mixed material and that the bond lengths and bond angles are distorted with the composition.

Abstract The local atomistic structure in bulk SixGe1−x alloys in the whole composition range 0 < x < 1 was investigated experimentally and theoretically. By extended X-ray absorption fine structure measurements in Czochralski-grown bulk SiGe crystals it is found that bulk SiGe is a random mixture and that the Ge–Ge, Ge–Si and Si–Si bond lengths maintain distinctly different lengths and vary in a linear fashion as a function of alloy composition across the entire composition range 0 < x < 1, in good agreement with expectations derived from the ab-inito electronic structure calculations. The results indicate that SiGe is a typical disorder material and that the bond lengths and bond angles are distorted with alloy composition in SiGe.

Abstract Transmission X-ray topograph was successfully observed in a high quality P-doped ZnTe substrate (100). The dislocation density was estimated to be approximately 7000 cm−2. This value was smallest in the ZnTe substrate. Both peak energies in the photoluminescence spectra were the same in the dislocation and no-dislocation areas. However, the intensity of the free-to-acceptor emission in the dislocation area was larger than that in the no-dislocation area. It was found that the majority of the phosphor impurities existed in the dislocation areas.

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The dynamic behavior of dislocations in highly impurity-doped Si crystals is investigated. Suppression of the generation of dislocations from a surface scratch is found for Si doped with B and P with a concentration higher than 1×1019cm-3and the critical stress for dislocation generation increases with B and P concentration which is interpreted in terms of dislocation locking due to impurity segregation. The velocity of dislocations in B- and P-doped crystals increases with increasing B and P concentration, respectively.

Plastic deformation of GaAs, InP, and InSb under hydrostatic confining pressure has been performed in the temperature range 77 to 500 K. Slip lines indicate cross-slip of screw dislocations. Electron microscopy reveals long screw dislocations left in the deformed specimens. The temperature dependence of the critical shear stress τc below 300 K is weak, producing a hump in the τc — T curve. The kink pair formation of non-dissociated screw dislocations in the shuffle set planes is responsible for the plastic deformation at low temperatures.

Z-shape faulted dipoles in deformed GaAs were investigated by using high resolution electron microscopy. There is no difference in the core structure of the α and β dislocations of stair-rod and 90° Shockley partials, nor in the dissociated stacking fault width. The central stacking fault is found to generate large local atomic displacements and exhibits a different structure from that of the intrinsic stacking fault of a dissociated dislocation considered so far. 90° Shockley partials of Z-shape faulted dipole climbed through absorption of interstitials during electron irradiation.

The dislocation velocities and mechanical strength of bulk crystals of Ge1—xSix alloys have been investigated by the etch pit technique and compressive deformation tests, respectively. The velocity of dislocations has been determined as a function of stress and temperature in the composition ranges 0 < x < 0.08 and 0.94 < x < 1. In the composition range 0 < x < 1 the yield stress showed a maximum around x = 0.5 and was dependent on the composition as being proportional to x(1—x). Built-in long-range internal stress fields in GeSi alloy caused by local fluctuations of the alloy composition together with dynamic development of the solute atmosphere around dislocations were thought to result in the strengthening of GeSi as a unique alloying effect.

In-situstraining experiments on dislocation motion in Ge and Si–5 at% Ge alloy single crystals are performed in a high voltage transmission electron microscope. In comparison with previous results by other methods, the dislocation velocities are found to be enhanced due to a recombination enhancement owing to the excess carrier injection by the electron beam. The reduction in the activation energy of dislocation motion is ascribed to the recombination-assisted kink formation. The kink migration energy is estimated to be 0.7 eV in Ge and 1.5 eV in SiGe.

Bulk crystals of Ge1−xSixalloys were grown by the Czochralski technique. Full single crystals were obtained for the alloys of composition 0 < x < 0.15 and 0.9 < x < 1, while single crystal parts near the seeds of ingots provided alloys of intermediate composition. The dislocation velocity and mechanical strength of the GeSi alloys were investigated by the etch pit technique and compressive deformation tests, respectively. In the GeSi alloys of the composition range 0.004 < x < 0.080 the dislocation velocity decreases monotonically with increasing Si content in the temperature range 450–700°C and the stress range 3–24 MPa. In contrast, in the composition range 0.94 < x < 1 the dislocation velocity first increases and then decreases with decreasing Si content in the temperature range 750–850°C and the stress range 3–30 MPa. The velocity of dislocations was determined as functions of stress and temperature. The stress–strain behaviour in the yield region of the GeSi alloys of composition 0 < x < 0.4 is similar to that of Ge at temperatures lower than about 600°C. However, the yield stress becomes temperature-insensitive at high temperatures and increases with increasing Si content. The stress–strain curves of the GeSi alloys of composition 0.94 < x < 1 are similar to those of pure Si at temperatures of 800–1000°C and the yield stress increases with decreasing Si content down to x = 0.94. The yield stress of the GeSi alloys is dependent on the composition, being proportional to x(1 − x). The strengthening mechanism in alloy semiconductors is discussed.

Floating-zone Si crystals enclosed in quartz ampoules were exposed to Zn vapour released by an elemental diffusion source. Penetration profiles of Zn in Si were recorded using the spreading-resistance technique or neutron activation analysis. Both the erfc-type distributions observed in plastically deformed specimens and the non-erfc profiles determined on dislocationfree wafers are consistently interpreted within the framework of the kick-out model. As an implication, Si self-interstitials generated in excess by interstitial-to-substitutional transitions of in-diffusing Zn atoms annihilate not only at the surface but also at dislocations. On the other hand, dislocation-induced segregation of Zn appears to be rather minor, as revealed by transition electron microscopy. Combining the Zn incorporation rate in dislocation-free Si with solubility data from saturated specimens yields the self-interstitial contribution to the Si self-diffusion coefficient.

The structural defects in annealed chalcopyrite AgGaS2single crystals grown by the vertical gradient freezing method were investigated using X-ray topography. Dislocations with Burgers vector of the type b=12[11¯1]moving on {112}, b= [001] on {010} and b= 〈100〉 on {010} were identified within the crystals, as distinct from the preferential activation of b=12[3¯11]dislocations on {112} in the related compound CuFeS2. Twins formed due to the motion of dislocations with pure screw character of b=16[111¯]on {112} were also observed as similarly found for CuFeS2.

Single crystal Ge1 − xSixalloys of composition 0 < x < 0.64 were grown by the Czochralski method. In particular, a single crystal 20 mm in diameter and 60 mm in length with variable composition 0.004 < x< 0.03 along the growth direction, and a crystal 12 mm in diameter and 20 mm in length with composition 0.21 < x< 0.25 were obtained. The crystals became Ge rich along the growth direction as determined by energy dispersive X-ray (EDX) spectroscopy. Fine striation structures in the crystals were observed by X-ray topography.

Bulk crystals of Ge1-xSixalloys in the composition range of 0 < x< 0.89 were grown by the Czochralski method. Fully or partly grown single crystals were obtained, depending on the melt composition. The compositions of grown crystals were determined by means of energy dispersive X-ray (EDX) spectroscopy and grown-in defects were observed by etch pit and X-ray topographic techniques. The variations of the compositions along the growth direction in the crystals were discussed. The gravity effect in the melt caused by a large difference in the densities of Ge and Si was deduced.

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A Vickers indentation method was used to determine the hardness of AlN and GaN, grown by the hydride vapor phase epitaxy technique, in the temperature range 20–1400 °C. At room temperature, the hardnesses of GaN and AlN are 10.2 and 17.7 GPa, respectively. The hardness of GaN and AlN shows a gradual decrease from RT and then a steep decrease from around 1000 °C. AlN is harder than GaN but softer than SiC. The steep decrease of the hardness means the beginning of macroscopic dislocation motion and plastic deformation. The mechanical strength of bulk single-crystal GaN is investigated at elevated temperatures directly by means of compressive deformation. The yield stress of GaN in the temperature range 900–1000 °C is around 100–200 MPa, i.e., similar to that of 6H-SiC and much higher than those of Si, Ge, GaAs.

The aim of all X-ray topographic methods is to provide a picture of the distribution of the defects in a crystal. By using Si(220) monochrometor irradiated by an incident beam of 3mm×0.1mm, the effect of annealing on texture of3He at about 0.3mK and of4He at about 0.5mK by the fixed point observation were taken on every three hours by emulsion plate, together with the diffraction patterns by scanning the incident beam over some extent near the vicinity of the fixed point. Annealing effect could not be observed in4He but it was very conspicuous in3He.

Electrical conduction along dislocations in plastically deformed n-GaN single crystals has been investigated by scanning spread resistance microscopy (SSRM). In the SSRM images, many conductive spots have been observed, which correspond to electrical conduction along the dislocations introduced by deformation. Here, the introduced dislocations are b=(a/3)<1210> edge dislocations parallel to the [0001] direction. The current values at the spots normalized to the background current value are larger than 100. Previous works have shown that grown-in edge dislocations in GaN are nonconductive. The high conductivity of the deformation-introduced edge dislocations in the present work suggests that the conductivity depends sensitively on the dislocation core structure.