Optical Anisotropy of β‐Rhombohedral Boron from 0.4 to 16 μm

Werheit, H.; Hausen, A.; Binnenbruck, H.

doi:10.1002/pssb.2220510110

Cited by 40 publications

(7 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed in this comparison is neglected respectively E u type are found allowing a largely certain correlation to one another, which is shown in Figure 9. From the anisotropy of the absorption edge [38] can be obtained that bonding _L c is slightly stronger than || c. This coincides with the E u vibration modes originating from F lu being more displaced relative to a certain center value than the A 2u modes. This center can be located at about 840 cm" 1 , which deviates only by 3.7% from the medium frequency 871 cm" 1 derived above using the mean B-B distance.…”

Section: Discussion Of the Spectra A) Pure ß-Rhombohedral Boronsupporting

confidence: 63%

Lattice Vibrations, MIR and FIR Optical Properties of Boron and Icosahedral Boron-Rich Borides II. β-Rhombohedral Structure Group

Werheit¹,

Haupt²,

Higashi

1990

Zeitschrift Für Naturforschung A

Self Cite

View full text Add to dashboard Cite

The lattice vibrations of the ß-rhombohedral boron structure group are investigated in detail by group theory. IR spectra of pure ß-rhombohedral boron as well as of B: Mn, B: Fe, B: Cu, and B: Cu/Al are presented and discussed. In comparison with boron carbide most of the absorption bands can be associated with certain vibrations. The vibration frequencies are determined by application of the phenomenological theory of Waser and Pauling, which thus yields a reliable estimation of the restoring forces ion these solides

show abstract

Section: Discussion Of the Spectra A) Pure ß-Rhombohedral Boronsupporting

confidence: 63%

Lattice Vibrations, MIR and FIR Optical Properties of Boron and Icosahedral Boron-Rich Borides II. β-Rhombohedral Structure Group

Werheit¹,

Haupt²,

Higashi

1990

Zeitschrift Für Naturforschung A

Self Cite

View full text Add to dashboard Cite

show abstract

“…Moreover was guaranteed by this diode that the intensity of the penetrating light was sufficiently low not to disturb the drift measurements by a direct photoexcitation in the range of the probes. According to the Lambert-Beer absorption law for the absorption coefficient K > 40 cm-' [14] this error does not exceed 4% at the first pair of probes and even lo-'% at the fifth pair.…”

Section: Measuring Equipmentmentioning

confidence: 87%

Ambipolar Diffusion of Electron–Hole Pairs in β‐Rhombohedral Boron

Werheit

Kristen

Franz

1992

Physica Status Solidi (b)

Self Cite

View full text Add to dashboard Cite

In &rhombohedra1 boron the electronic transport is essentially determined by deep electron traps of different bonding energies. The ambipolar diffusion of optically excited electron-hole pairs on diffusion paths of up to 5.37 mm length was investigated. The diffusion length at stationary conditions is 21 mm and the mean diffusion velocity is 5.8 x m s-'. From these data a lifetime of 3620 s results. By Fick's secondlaw the diffusion coefficient wasdetermined to increasefrom about 5 x to 10' cm2 s-' with the diffusion velocity increasing from lo-' to lo-' m s-'. The Einstein relation yields thc corresponding mobilities, which increase accordingly from about 0.2 to about 50 cm2 V s-. These mobilities are mean values for electrons and holes. The relaxation of the excited state of the sample into the thermal equilibrium is determined by five relaxation times (6.6, 50, 514, 5650, 14700 s), which are immediately related to the thermal excitation of the electrons from the traps with the bond energies 0.18, 0.37, 0.58, 0.77, and 0.89 eV.In 0-rhomboedrischem Bor wird der elektronische Transport im wesentlichen durch tiefe Elektronenhaftstellen mit versehiedenen Bindungsenergien bestimmt. Die ambipolare Diffusion optisch angeregter Elektron-Loch-Paare auf Diffusionswegen von bis zu 5,37 mm Lange wird untersucht. Unter stationaren Bedingungen betragt die Diffusionslange 21 mm und die mittlere Diffusionsgeschwindigkeit 5,8 x m s-', woraus sich eine Lebensdauer von 3620 s ergibt. GemaB dem zweiten Fick'schen Gesetz wird gefunden, daB der Diffusionskoefizient von 5 x auf 10 cm2 s -' anwiichst, wenn die Diffusionsgeschwindigkeit von lo-' auf lo-' m s-l steigt. Die Einsteinbeziehung ergibt die entsprechenden Beweglichkeiten, die von etwa 0,2 auf 50cm2 V-' s -' anwachsen. Diese Beweglichkeiten sind Mittelwerte fur Elektronen und Locher. Die Relaxation des Anregungszustandes der Probe im thermischen Gleichgewichtszustand wird durch funf Relaxationszeiten (6,6; 50; 514; 5650; 14700 s) bestimmt, die unmittelbar mit der thermischen Anregung von Elektronen aus Haftstellen mit Bindungsenergien von 0,lS; 0,37; 0,58; 0,77 und 0,89 eV verkniipft sind.') Postfach 101 503, W-4100 Duisburg, FRG.

show abstract

“…According to Werheit's evaluation of the density of states (DOS) of the acceptor levels from optical absorption experiments, the DOS is very high (10-10 cm\) (1). Electrical conductivity experiments show hopping type conduction over a wide range of temperature ((250 K) (4,5). In this temperature range, most of the carriers contributing to current are populated in the acceptor levels, rather than in the conduction or valence band.…”

mentioning

confidence: 97%