Influence of temperature upon dislocation mobility and elastic limit of single crystal HgI2

Milstein, Frederick; Farber, Bruce; Kim, K.; Schnepple, W.F.

doi:10.1016/0167-5087(83)90043-1

Cited by 36 publications

(9 citation statements)

References 8 publications

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“…12c, that is the direction of easy glide of basal plane dislocations and als0 the direction of hard glide of forest dislocations in the [0 1 0] plane [13], corroborates this second formation mechanism. The "third type of inclusions" barely observed by Milstein et al [14] in vapour grown cz-HgI 2 (EG&G $4-25 and $2-20) crystals actually appear to be hohlstellen.…”

Section: Hohlstellenmentioning

confidence: 94%

“…But the energy resolution of the detectors is still depressed by a high concentration of different kind of extended defects easily accomodated in the ~-HgI2 layered lattice. The presence of different extended structural defects was mentioned in some papers [2~], others were devoted to their study [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

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Extended structural defects in ?-Hgl2 single crystals

Nicolau

Dupuy

Rolland

1993

J Mater Sci: Mater Electron

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Extended structural defects in both ~-Hgl 2 crystals grown in solution or from the vapourphase were studied by optical microscopy, light scattering, SEM operated in cathodoluminescence and in secondary electron mode, X-ray topography, neutron, y-and X-ray rocking curves and oscillating crystal X-ray diffraction. The observed dislocations were compared with theoretically calculated dislocations. Dislocation loops, having diameters ranging from 2 gm to 500 gm, are observed on all low index faces, Hohlstellen (lens-shaped voids) having axes along the [001] direction, less than 1 gm in thickness, and diameters lying in the (001) planes, ranging from 2 gm to 10 gm are characteristic defects. Observed plastic deformations like glide sheets and bands, tilt and twist boundaries, kink and fatigue bands, ridges and rumplings were characterized. Growth rings, spherical void inclusions 10-30 gm in diameter, orthogonal walls of forest screw dislocations parallel to {1 00} planes, and streaks (planar void sheets crossing the (001 ) planes) were only observed in crystals grown from the vapour-phase. Cross-penetration twins having {1 1 4} twin planes are described. The possible formation of stacking faults was analysed. The mosaicity of solution-grown crystals ranges from 1' to 6'. A characteristic cellular structure, having a cell size ranging from 2 I~m to 10 gm, was observed in all the crystals examined and correlated to local deviations from the stoichiometric composition. Solid lens-shaped inclusions, having diameters ranging from 3 gm to 500 gm and thicknesses ranging from 0.3 gm to 50 gm, respectively, are entrapped in many crystals and correlated to spiral hillocks observed on {0 01 } growing faces.

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Section: Hohlstellenmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Extended structural defects in ?-Hgl2 single crystals

Nicolau

Dupuy

Rolland

1993

J Mater Sci: Mater Electron

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“…15 As part of those studies, two types of localized structural anomaly were observed optically following the etching of wafers from terrestrial crystals that had been grown both from mercuryrich and from stoichiometric material. 16 Linear ͗110͘ arrays of small, round inclusions were found. Individual linear ͗100͘ anomalies also were observed.…”

Section: B Preceding Structural Informationmentioning

confidence: 98%

“…Because of its intrinsic importance for the development of radiation detectors, the defect structure of mercuric iodide has been investigated by a range of techniques: optical observation, 15 etching, 16 ␥-ray diffraction, 2 calorimetry, 17 a͒ Author to whom correspondence should be addressed. b͒ Work carried out while the author was at EG&G Energy Measurements, Goleta, California.…”

Section: B Preceding Structural Informationmentioning

confidence: 99%

Enhancement of mercuric iodide detector performance through increases in wafer uniformity by purification and crystal growth in microgravity

Steiner

Laor

1999

Journal of Applied Physics

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Wafers from mercuric iodide crystals grown in microgravity on two occasions have previously been found to be characterized by a higher hole mobility-lifetime product, which enables energy dispersive radiation detectors with superior resolution. In the present work, we have identified the specific structural modifications that are responsible for this enhanced performance. As a result of this study, the performance of terrestrial wafers also has been improved but not yet to the level of wafers grown in microgravity. High resolution synchrotron x-ray diffraction images of a series of wafers, including those grown both in microgravity and on the ground, reveal two principal types of structural changes that are interrelated. One of these, arrays of inclusions, affects performance far more strongly than the other, variation in lattice orientation. Inclusions can be formed either from residual impurities or in response to deviations from ideal stoichiometry. The formation of both types is facilitated by gravity-driven convection during growth. As the level of inclusions is reduced, through growth from material of higher purity, through the achievement of balanced stoichiometry, or by suppression of convection mixing during crystal growth, the hole mobility-lifetime product is enhanced in spite of an accompanying decreased uniformity in lattice orientation. Sixfold enhancement in the performance of x-and ␥-ray detectors has been accomplished to date. Further augmentation in performance appears likely.

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“…Others have reported on defects which we interpret as being identical to X-defects. 17 18 Milstein et al 18 observed three types of inclusions with photo-microscopy. One of those we interpret as X-defects were described by the authors as short line segments aligned in <100> directions and were "apparently" parallel to the (001).…”

Section: X-defectsmentioning

confidence: 98%

Characterization of strain and crystallographic defects in HgI 2 single crystals

Alexander

Sandoval

2004

SPIE Proceedings

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We investigated bulk-grown HgI 2 crystals to better understand the nature of crystallographic defects and strain/stress in different growth regions of the crystal and their affect on the performance of HgI 2 -based radiation detectors. Doubleaxis and triple-axis high-resolution x-ray diffraction were used to characterize the mosaic structure and strain in HgI 2 . Rocking curves revealed significant mosaic spreading in <110> growth regions exhibiting X-defects versus X-defectfree <100> growth regions. Both <110> and <100> growth regions exhibited little strain (~0.01%). We report the narrowest rocking curves (~ 9 arcsec) to date on HgI 2 as a result of the resolution of the instrument (~ 6 arcsec). Raman spectroscopy was used collaboratively to confirm little residual stress in the crystals. We developed a growth rate ratio (χ) and show this geometric model used to describe crystal shape and regions of <100> and <110> growth. Optical characterization of X-defects are presented and discussed. Further the influence of crystallographic defects and strain on radiation detector performance are discussed.

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Influence of temperature upon dislocation mobility and elastic limit of single crystal HgI2

Cited by 36 publications

References 8 publications

Extended structural defects in ?-Hgl2 single crystals

Extended structural defects in ?-Hgl2 single crystals

Enhancement of mercuric iodide detector performance through increases in wafer uniformity by purification and crystal growth in microgravity

Characterization of strain and crystallographic defects in HgI 2 single crystals

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