Temperature Dependence of Electroluminescence from Nanocrystalline Silicon thin Films

1998 ◽  
Vol 507 ◽  
Author(s):  
T. Toyama ◽  
Y. Kotani ◽  
A. Shimode ◽  
K. Shimizu ◽  
H. Okamoto
Keyword(s):  
Thin Films ◽  
Temperature Dependence ◽  
Ultraviolet Light ◽  
Blue Shift ◽  
Nanocrystalline Silicon ◽  
Peak Shift ◽  
Generation Rate ◽  
Carrier Generation ◽  
Silicon Thin Films ◽  
Nanocrystalline Si

ABSTRACTTemperature dependence of electroluminescence (EL) from nanocrystalline Si (nc-Si) has been studied in comparison with that of photoluminescence (PL) from the nc-Si. The similarity is found in the temperature dependence of peak shift between EL and PL excited by ultraviolet light. The blue shift in both peaks is also found when the carrier generation rate is increased. The experimental results are indicative that the peak shifts due to the temperature and the generation rate are based on different mechanisms.

Optical Transitions in Light-Emitting Nanocrystalline Silicon Thin Films

1999 ◽  
Vol 557 ◽  
Author(s):  
T. Toyama ◽  
Y. Kotani ◽  
A. Shimode ◽  
S. Abo ◽  
H. Okamoto
Keyword(s):  
Thin Films ◽  
Crystal Size ◽  
Nanocrystalline Silicon ◽  
Optical Transitions ◽  
Direct Transition ◽  
Light Emitting ◽  
Silicon Thin Films ◽  
Peak Energy ◽  
The Mean ◽  
Nanocrystalline Si

AbstractOptical transitions in nanocrystalline Si (nc-Si) thin films with different mean crystal sizes ranging from < 2 nm to ~3 nm have been studied by electroreflectance (ER) spectroscopy. At 293 K, ER signals are observed at 1.20-1.37 eV to be corresponding to fundamental gap in bulk crystalline Si. With a decrease in the mean crystal sizes of nc-Si, the transition energy of the fundamental gap is increased and the ER signal is intensified. The bandgap widening would be due to quantum confinement (QC) in nc-Si, and the increased signal indicates appearance of direct transition nature. The ER signals are also observed at 2.2 eV and at E1 (E0’) direct gap of 3.1-3.4 eV, while photoluminescence (PL) peak energies are located at 1.65-1.75 eV and at 2.3 eV. With the reduced mean crystal size, the 1.7-eV PL peak energy is also increased, suggesting that QC is also responsible for the increased PL peak energy.

Thermoelectric properties of doped and undoped mixed phase hydrogenated amorphous/nanocrystalline silicon thin films

2010 ◽  
Vol 1245 ◽  
Author(s):  
James Kakalios ◽  
Yves Adjallah ◽  
Charlie Blackwell
Keyword(s):  
Thin Films ◽  
Seebeck Coefficient ◽  
Temperature Dependence ◽  
Nanocrystalline Silicon ◽  
Dark Conductivity ◽  
Mixed Phase ◽  
Positive Temperature ◽  
Silicon Thin Films ◽  
Similar Temperature Dependence ◽  
Hydrogenated Amorphous

AbstractThe Seebeck coefficient and dark conductivity for undoped, and n-type doped thin film hydrogenated amorphous silicon (a-Si:H), and mixed-phase films with silicon nanocrystalline inclusions (a/nc-Si:H) are reported. For both undoped a-Si:H and undoped a/nc-Si:H films, the dark conductivity is enhanced by the addition of silicon nanocrystals. The thermopower of the undoped a/nc-Si:H has a lower Seebeck coefficient, and similar temperature dependence, to that observed for undoped a-Si:H. In contrast, the addition of nanoparticles in doped a/nc-Si:H thin films leads to a negative Seebeck coefficient (consistent with n-type doping) with a positive temperature dependence, that is, the Seebeck coefficient becomes larger at higher temperatures. The temperature dependence of the thermopower of the doped a/nc-Si:H is similar to that observed in unhydrogenated a-Si grown by sputtering or following high-temperature annealing of a-Si:H, suggesting that charge transport may occur via hopping in these materials.

Characterization of hydrogenated nanocrystalline silicon thin films prepared with various negative direct current biases

2008 ◽  
Vol 23 (3) ◽  
pp. 790-797 ◽  
Author(s):  
Jae-Hyun Shim ◽  
Nam-Hee Cho ◽  
El-Hang Lee ◽  
Han-Sup Lee
Keyword(s):  
Thin Films ◽  
Direct Current ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Relative Fraction ◽  
Silicon Thin Films ◽  
Dc Bias ◽  
Frequency Power ◽  
Nanocrystalline Si

Hydrogenated nanocrystalline Si (nc-Si:H) thin films were prepared by plasma- enhanced chemical vapor deposition (PECVD). The films were deposited with a radio-frequency power of 100 W, while substrates were exposed to direct current (dc) biases in the range from 0 to −400 V. The effects of dc bias on the formation of nanoscale Si crystallites in the films and on their optical characteristics were investigated. The size of the Si crystallites in the films ranges from ∼1.9 to ∼4.1 nm. The relative fraction of the crystallites in the films reached up to ∼56.5% when a dc bias of −400 V was applied. Based on the variation in the structural, chemical, and optical features of the films with dc bias voltages, a model for the formation of nanostructures of the nc-Si:H films prepared by PECVD was suggested. This model can be utilized to understand the evolution in the size and relative fraction of the nanocrystallites as well as the amorphous matrix in the nc-Si:H films.

Giant Anisotropy of Conductivity in Hydrogenated Nanocrystalline Silicon Thin Films

1998 ◽  
Vol 536 ◽  
Author(s):  
A. B. Pevtsov ◽  
N. A. Feoktistov ◽  
V. G. Golubev
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Percolation Theory ◽  
Nanocrystalline Silicon ◽  
Spatial Light Modulators ◽  
Light Emitting ◽  
Light Modulators ◽  
Silicon Thin Films ◽  
Longitudinal Conductivity ◽  
Transverse Conductivity

AbstractThin (<1000 Å) hydrogenated nanocrystalline silicon films are widely used in solar cells, light emitting diodes, and spatial light modulators. In this work the conductivity of doped and undoped amorphous-nanocrystalline silicon thin films is studied as a function of film thickness: a giant anisotropy of conductivity is established. The longitudinal conductivity decreases dramatically (by a factor of 109 − 1010) as the layer thickness is reduced from 1500 Å to 200 Å, while the transverse conductivity remains close to that of a doped a- Si:H. The data obtained are interpreted in terms of the percolation theory.

Temperature dependence of the transient and AC electrical conductivity of porous silicon thin films

2003 ◽  
Vol 101 (1-3) ◽  
pp. 334-337 ◽  
Author(s):  
M. Theodoropoulou ◽  
C.A. Krontiras ◽  
N. Xanthopoulos ◽  
S.N. Georga ◽  
M.N. Pisanias ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Porous Silicon ◽  
Temperature Dependence ◽  
Ac Electrical Conductivity ◽  
Silicon Thin Films

Nanocrystalline silicon thin films prepared by radiofrequency magnetron sputtering

2002 ◽  
Vol 403-404 ◽  
pp. 91-96 ◽  
Author(s):  
C. Gonçalves ◽  
S. Charvet ◽  
A. Zeinert ◽  
M. Clin ◽  
K. Zellama
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Nanocrystalline Silicon ◽  
Silicon Thin Films
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