Understanding ion-milling damage in Hg1−xCdxTe epilayers

Wang, Changzhen; Smith, David J.; Tobin, S. P.; Parodos, T.; Zhao, Jun; Chang, Yong; Sivananthan, S.

doi:10.1116/1.2207148

Cited by 36 publications

(25 citation statements)

References 27 publications

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“…The TEM measurements have been discussed in detail elsewhere, 10,[22][23][24][25] including the additional steps required to reduce ion-milling damage and preparation artefacts. 25 …”

Section: Methodsmentioning

confidence: 99%

Surface Morphology and Defect Formation Mechanisms for HgCdTe (211)B Grown by Molecular Beam Epitaxy

Chang

Becker

Grein

et al. 2008

Journal of Elec Materi

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The surface morphology and crystallinity of HgCdTe films grown by molecular beam epitaxy (MBE) on both CdZnTe and CdTe/Si (211)B substrates were characterized using atomic force microscopy (AFM), as well as scanning (SEM) and transmission (TEM) electron microscopy. Crosshatch patterns and sandybeach-like morphologies were commonly found on MBE (211) HgCdTe epilayers grown on both CdZnTe and CdTe/Si substrates. The patterns were oriented along the 213 Â Ã , 231 Â Ã , and 011 Â Ã directions, which were associated with the intersection between the (211) growth plane and each of the eight equivalent HgCdTe slip planes. This was caused by strain-driven operation of slip in these systems with relative large Schmid factor, and was accompanied by dislocation formation as well as surface strain relief. Surface crater defects were associated with relatively high growth temperature and/or low Hg flux, whereas microtwins were associated with relatively low growth temperature and/or high Hg flux. AFM and electron microscopy were used to reveal the formation mechanisms of these defects. HgCdTe/HgCdTe superlattices with layer composition differences of less than 2% were grown by MBE on CdZnTe substrates in order to clarify the formation mechanisms of void defects. The micrographs directly revealed the spiral nature of growth, hence demonstrating that the formation of void defects could be associated with the Burton, Cabrera, and Frank (BCF) growth mode. Void defects, including microvoids and craters, were caused by screw defect clusters, which could be triggered by Te precipitates, impurities, dust, other contamination or flakes. Needle defects originated from screw defect clusters linearly aligned along the 011 Â Ã directions with opposite Burgers vector directions. They were visible in HgCdTe epilayers grown on interfacial superlattices. Hillocks were generated owing to twin growth of void or needle defects on (111) planes due to low growth temperature and the corresponding insufficient Hg movement on the growth surface. Therefore, in addition to nucleation and growth of HgCdTe in the normal two-dimensional layer growth mode, the BCF growth mode played an important role and should be taken into account during investigation of HgCdTe MBE growth mechanisms.

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“…The TEM measurements have been discussed in detail elsewhere, 10,[22][23][24][25] including the additional steps required to reduce ion-milling damage and preparation artefacts. 25 …”

Section: Methodsmentioning

confidence: 99%

Surface Morphology and Defect Formation Mechanisms for HgCdTe (211)B Grown by Molecular Beam Epitaxy

Chang

Becker

Grein

et al. 2008

Journal of Elec Materi

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“…The mechanical polishing and dimpling typically reduced the sample thicknesses to 10$12 lm, and small holes in the films were then made by ion-milling at low energy (2.5$3 keV), using a liquid-nitrogen-temperature cooling stage to minimize any thermal or ion-beam damage. 27 The TEM characterization studies were mostly carried out using a JEM-4000EX high-resolution electron microscope operated at 400 keV and with a structural resolution of $1.7 Å . All samples were prepared for observation along {110}-type zone-axis projections so that the direction of the electron beam would be aligned perpendicular to the growth surface normal.…”

Section: Methodsmentioning

confidence: 99%

Structural properties of InAs/InAs1–xSbx type-II superlattices grown by molecular beam epitaxy

Ouyang¹,

Steenbergen²,

Zhang³

et al. 2011

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Strain-balanced InAs/InAs1−xSbx type-II superlattices (SLs) have been proposed for possible long-wavelength infrared applications. This paper reports a detailed structural characterization study of InAs/InAs1−xSbx SLs with varied Sb composition grown on GaSb (001) substrates by modulated and conventional molecular beam epitaxy (MBE). X-ray diffraction was used to determine the SL periods and the average composition of the InAs1−xSbx alloy layers. Cross-section transmission electron micrographs revealed the separate In(As)Sb/InAs(Sb) ordered-alloy layers within individual InAs1−xSbx layers for SLs grown by modulated MBE. For the SLs grown by conventional MBE, examination by high-resolution electron microscopy revealed that interfaces for InAs1−xSbx deposited on InAs were more abrupt, relative to InAs deposited on InAs1−xSbx: this feature was attributed to Sb surfactant segregation occurring during the SL growth. Overall, these results establish that strain-balanced SL structures with excellent crystallinity can be achieved with proper design (well thickness versus Sb composition) and suitably optimized growth conditions.

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“…These observations were made before we fully appreciated the importance of ensuring that the sample was really at liquid-nitrogen temperature during ion milling. 6 It was found that the p-type layer was generally of high quality. Small defects were, however, visible in the region of the p-n junction and in both n and p layers, although the density of defects in the p-type layer was much lower.…”

Section: Resultsmentioning

confidence: 98%