Lattice bands in germanium

“…In the spectral region under study pure germanium has broad absorption bands associated with two-phonon processes [20] (curve 3). The large background is associated with free-carrier absorption due to incomplete compensation.…”

Section: Resultsmentioning

confidence: 99%

Infrared Absorption by Local Vibrational Modes of Boron Impurities in Germanium

Nazarewicz¹,

Jurkowski²

1969

Physica Status Solidi (b)

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Local modes of boron in germanium have been observed b y infrared absorption measurements in the range from 480 to 630 cm-l a t 195 and 295 OK. Lithium has been used as a compensating donor impurity. The absorption spectrum contains three pairs of bands which are attributed t o local modes of boron on the basis of the isotopic shifts observed. One of these pairs is associated with unpaired (isolated) boron and two others with boron in paired configuration (with lithium), as was predicted theoretically. A comparison of our data with those already known for silicon is given.Les modes localises du bore dans le germanium ont kt6 observes par des mesures dabsorption infrarouge dans la region de 480 A 630 cm-' iL 195 et 295 "K. Le lithium a BtB utilise comme impureti. compensatrice. Le spectre d'absorption contient trois paires de bandes qui sont attribuees aux modes locaux du bore sur la base des dkplacements isotopiques observes. L'une de ces paires est attributee au bore isole et deux autres au bore associe au lithium, conformement aux previsions theoriques. Ces rbsultats sont compares B ceux d6jh connus dans le silicium.

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“…Between 11.5 and 14 µm lattice absorption ranges from 0.15 to 0.25/cm at 293 K and from 0.06 to 0.09/cm at 77K and below 7 . This would result in unacceptable absorption in a large grating, imposing a long wave limit of about 11.5 µm.…”

Section: Materials Limitationsmentioning

confidence: 99%

Materials and fabrication issues for large machined germanium immersion gratings

et al. 2006

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LLNL has successfully fabricated small (1.5 cm 2 area) germanium immersion gratings. We studied the feasibility of producing a large germanium immersion grating by means of single point diamond flycutting. Our baseline design is a 63.4º blaze echelle with a 6 cm beam diameter. Birefringence and refractive index inhomogeneity due to stresses produced by the crystal growth process are of concern. Careful selection of the grating blank and possibly additional annealing to relieve stress will be required. The Large Optics Diamond Turning Machine (LODTM) at LLNL is a good choice for the fabrication. It can handle parts up to 1.5 meter in diameter and 0.5 meter in length and is capable of a surface figure accuracy of better than 28 nm rms. We will describe the machine modifications and the machining process for a large grating. A next generation machine, the Precision Optical Grinder and Lathe (POGAL), currently under development has tighter specifications and could produce large gratings with higher precision.

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Lattice bands in germanium

Cited by 47 publications

References 6 publications

Band‐to‐Band Radiative Recombination in Groups IV, VI, and III–V Semiconductors (II)

Band‐to‐Band Radiative Recombination in Groups IV, VI, and III–V Semiconductors (II)

Infrared Absorption by Local Vibrational Modes of Boron Impurities in Germanium

Materials and fabrication issues for large machined germanium immersion gratings

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