A material innovation for the electronic industry: float zone single crystal silicon with 200mm diameter

Altmannshofer, L.; Grundner, M.; Virbulis, J.; Hage, Johannes

doi:10.1109/ispsd.2003.1225293

Cited by 6 publications

(7 citation statements)

References 2 publications

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“…The most visually striking features in the flats are concentric circles, commonly known as "tree rings" (see Figure 1). They originate from circularly symmetric variations in impurity concentrations that arise during the growth of single-crystal silicon from polysilicon (see Figure 5 in Altmannshofer et al (2003)). 6 If the density of doping impurities is not uniform in the direction parallel to the back-side of the CCD (the x direction), a difference in space charges will generate a transverse field E ⊥ , perpendicular to the optical axis of the detector (the y direction).…”

Section: The Dark Energy Survey and The Dark Energy Cameramentioning

confidence: 99%

On-Sky Measurements of the Transverse Electric Fields’ Effects in the Dark Energy Camera CCDs

Plazas¹,

Bernstein²,

Sheldon³

2014

Publications of the Astronomical Society of the Pacific

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Photo-generated charge in thick, back-illuminated, fully-depleted CCDs is transported by electric fields from the silicon substrate to the collecting well at the front gate of the CCDs. However, electric fields transverse to the surface of the CCD -with diverse origins such as doping gradients, guard rings around the imaging area of the sensor, and physical stresses on the silicon lattice-displace this charge, effectively modifying the pixel area and producing noticeable signals in astrometric and photometric measurements. We use data from the science verification period of the Dark Energy Survey (DES) to characterize these effects in the Dark Energy Camera (DECam) CCDs. The transverse fields mainly manifest as concentric rings (tree rings) and bright stripes near the boundaries of the detectors (edge distortions) with relative amplitudes of about 1% and 10% in the flat-field images, respectively. Their nature as pixel size variations is confirmed by comparing their photometric and astrometric signatures. Using flat-field images from DECam, we derive templates in the five DES photometric bands (grizY ) for the tree rings and the edge distortions as a function of their position in each DECam detector. These templates can be directly incorporated into the derivation of photometric and astrometric solutions, helping to meet the DES photometric and astrometric requirements.

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Section: The Dark Energy Survey and The Dark Energy Cameramentioning

confidence: 99%

On-Sky Measurements of the Transverse Electric Fields’ Effects in the Dark Energy Camera CCDs

Plazas¹,

Bernstein²,

Sheldon³

2014

Publications of the Astronomical Society of the Pacific

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“…They consist of concentric variations of the flat-field response to a uniform illumination. The center of the circles coincides with the center of the ingot from which the sensor was manufactured, as discussed in [5]. On DECam, these variations amount to about 0.2% (y band) to 0.4% (g band) peak to peak [6], and the patterns look alike in different bands.…”

Section: Tree Ringsmentioning

confidence: 78%

“…The physical picture one can draw is the following: during the growth of the silicon boule, there are time-dependent variations of silicon purity, which translate into small static distortions of the drift field in the sensor [5,6]. Those distortions in turn displace the image in a positiondependent way and the divergence of the displacement field is observed as pixel size variations imprinted on flat-field images.…”

Section: Tree Ringsmentioning

confidence: 99%

An introduction to some imperfections of CCD sensors

Astier¹

2015

J. Inst.

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CCD sensors do not deliver a perfect image of the light they receive. Beyond the well known linear image smearing due to diffusion of charges during their drift towards the pixel wells, non-linear effects are at play in these sensors. We now have ample evidence for both a fluxdependent and static image distortions, especially but not only, on deep-depleted CCDs. For large surveys relying on CCD sensors, these effects should now be taken into account when reducing data. We present here a summary of current results on sensor characterization and mitigation methods.

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“…ACRT becomes even important for crucible-free floating zone (FZ) growth of oxygenfree large-diameter (200 mm) silicon crystals [50,51]. To overcome the difficulty of growth front break out in the radial direction, especially at large diameters, the growing crystal is periodically rotated through a sequence of rotation angles.…”

Section: Acrt In Group-iv Growthmentioning

confidence: 99%