Injection Level and Temperature Dependence of the Recombination Activity of Grain Boundaries in Germanium

ABSTRACTGrain boundaries in polycrystalline silicon are most likely to generate localized states in band gap. The localized states play a dominant role in determining the performance of solar cells by acting as traps or recombination center of carriers. In the present investigation, the scanning electron microscope - electron channeling pattern(SEM/ECP) method and SEM - electron back scattered diffraction pattern(SEM/EBSD) technique were applied to characterize the grain boundaries in p-type polycrystalline silicon with 99.999%(5N) in purity. Thereafter, temperature dependence of electrical activity of individual grain boundaries was measured by an electron beam induced current(EBIC) technique.It has been found that temperature dependence of EBIC contrast at grain boundaries can change, depending on the misorientation angle the orientation of the boundary plane. The results can be explained by the difference in the position of the localized state within the band gap on the basis of the Shockley-Read-Hall statistics. The {111} ∑3 symmetrical tilt boundary has shallow states, while high ∑ boundaries have deep states. Low angle boundaries reveal high electrical activities. The EBIC contrast at low angle boundaries was found to increase with increasing misorientation angle up to 2° followed by an almost constant value. High electrical activity at low angle boundaries is probably attributed to a stress field of primary dislocations forming low angle boundaries.

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The Temperature Dependence of Point Defect Cluster Formation and Binding Energies in Noble Metals Twist Grain Boundaries

Materials Science Forum ◽

10.4028/www.scientific.net/msf.126-128.249 ◽

1993 ◽

Vol 126-128 ◽

pp. 249-252

Author(s):

J.-M. Cayphas ◽

M. Hou

Keyword(s):

Temperature Dependence ◽

Grain Boundaries ◽

Point Defect ◽

Noble Metals ◽

Cluster Formation ◽

Defect Cluster ◽

Binding Energies

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Temperature and annealing dependence of the longitudinal ultrasonic velocity in aluminum alloys

Journal of Materials Research ◽

10.1557/jmr.1993.1558 ◽

1993 ◽

Vol 8 (7) ◽

pp. 1558-1566 ◽

Cited By ~ 5

Author(s):

Ward Johnson ◽

F. Mauer ◽

D. Pitchure ◽

S.J. Norton ◽

Y. Grinberg ◽

...

Keyword(s):

Aluminum Alloys ◽

Temperature Dependence ◽

Grain Boundaries ◽

Elevated Temperatures ◽

Low Frequency ◽

Additional Contribution ◽

Linear Temperature Dependence ◽

Linear Temperature ◽

Nonlinear Temperature Dependence ◽

Velocity Changes

The longitudinal ultrasonic velocities of four commercial aluminum alloys and Al(1.8 wt.% Si) were measured between room temperature and the solidus temperatures. In all of the samples, the velocity deviated significantly from a linear temperature dependence at the highest temperatures. In commercially pure (1100) aluminum, this effect is found to be consistent with reported low-frequency damping and elastic modulus changes that are associated with dislocations or grain boundaries. In the four heat-treatable alloys studied, an additional contribution to the nonlinear temperature dependence arises from the dissolution of precipitates at elevated temperatures. Irreversible velocity changes occur during the first heating, as a result of the recovery from work-hardening and heat treatments which were performed during the production of the material. Small hysteretic changes above ∼ 250 °C are correlated with the precipitation and dissolution of alloying elements. The activation energy for the hysteretic changes in Al(1.8% Si) is found to be 0.82 eV, which is consistent with precipitation limited by silicon diffusion along grain boundaries.

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