Surface structure of plasma-etched (211)B HgCdTe

X-ray diffraction full-width at half-maximum (XRD FWHM), reflection highenergy electron diffraction (RHEED), and atomic force microscopy (AFM) indicate a mosaic structure for molecular-beam epitaxy (MBE) (211)B CdTe/Si. AFM measurements indicate long, thin, small-angle-disoriented grains for CdTe/Si epilayers. These disoriented grains are $1 lm in the [111] direction and are $40 nm in the [011] direction. The RHEED pattern in the [111] direction depicts nearly ideal single-crystal periodicity. The RHEED pattern in the [011] direction is indicative of small-angle-disoriented crystalline grains. Scanning electron microscopy (SEM), AFM, and XRD measurements all indicate an approximate factor of 10 increase in the Everson etch pit density (EPD) over standard Nomarski microscopy Everson EPD determination.

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“…The RHEED patterns produced from a kinematic (no multiple scattering) model 26 for the ideal (211)B CdTe surface are shown in Fig. 2.…”

Section: Resultsmentioning

confidence: 99%

Structural Analysis of CdTe Hetero-epitaxy on (211) Si

Benson

Jacobs

Markunas

et al. 2008

Journal of Elec Materi

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“…It has been demonstrated to be a valuable nondestructive multipurpose microscopic research tool for studying HgCdTe-related materials. [9][10][11][12][13][14][15][16][17][18][19][20][21] In this work, a Veeco D3100 scanning probe microscopy (SPM) system configured for tapping-mode operation was used for AFM measurements. A 1-X Si tapping-mode tip/ cantilever with a backside Al reflective enhancement coating was employed to obtain good signal-tonoise ratio.…”

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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“…A more complete examination of as-grown HgCdTe surfaces can be found in Ref. 16. The x value of the bulk HgCdTe of these samples was 0.234.…”

Section: Ex Vacuo Atomic Force Microscopymentioning

confidence: 99%

“…It is significantly better than the 0.05% Br:ethylene glycol etched surface RMS roughness of 2.7 nm over an area of 50 lm · 50 lm. 16 The 0.3 nm RMS degradation in the (111) HgCdTe is primarily due to micropits that form. These pits are typically shallow and may also be due to the defects in the HgCdTe.…”

Section: Ex Vacuo Atomic Force Microscopymentioning

confidence: 99%

Morphology of Inductively Coupled Plasma Processed HgCdTe Surfaces

Stoltz

Benson

Smith

2008

Journal of Elec Materi

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Inductively coupled plasma (ICP) processing has become the industrial processing standard for HgCdTe and its related II-VI compounds. In this study ICP processes were developed that allow several microns of HgCdTe to be plasma etched while maintaining a low root-mean-square (RMS) roughness, and even improving the surface roughness in the case of HgCdTe-on-Si. These ICP processes are superior to older electron cyclotron resonance (ECR) plasma etches. The resulting ICP plasma processed surfaces are oxygen and carbon free, have a good reflection high-energy electron diffraction (RHEED) pattern, and have only a small amount of mercury depletion, x = 0.22 to 0.47 (where x is the ratio of Cd to Hg), in the first 25 Å to 30 Å of the HgCdTe. Nanofeatures of the as-grown HgCdTe are retained during the process and are believed to be indicative of the fundamental defect mechanisms in the different HgCdTe etched surfaces. Results from these experiments strongly suggest that ICP plasma processes can be used to delineate pixels, etch vias, clean surfaces, and even produce epi-ready surfaces that would allow HgCdTe to become much more manufacturable, and perhaps allow the replacement of wet processing in HgCdTe.

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Surface structure of plasma-etched (211)B HgCdTe

Cited by 9 publications

References 23 publications

Structural Analysis of CdTe Hetero-epitaxy on (211) Si

Structural Analysis of CdTe Hetero-epitaxy on (211) Si

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

Morphology of Inductively Coupled Plasma Processed HgCdTe Surfaces

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