Optical Phenomena at the Absorption Edge of Crystalline and Amorphous Silicon

1990 ◽  
Vol 192 ◽  
Author(s):  
George D. Cody
Keyword(s):  
Optical Properties ◽  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Absorption Edge ◽  
Crystalline Silicon ◽  
Dipole Matrix Element ◽  
Silicon Hydride ◽  
Energy Gaps ◽  
Site Disorder ◽  
Optical Phenomena

ABSTRACTOptical phenomena associated with the absorption edge of crystalline silicon (c-Si) and amorphous silicon hydride (a-Si:H) are presented and compared. The optical properties discussed include the energy dependence, dipole matrix element and density of states associated with the absorption edge; the temperature dependence of the relevant optical energy gaps, and finally the magnitude and temperature dependence of the slope of the Urbach edge for each material. The comparison suggests that the optical properties of the two materials are closely related and that the absorption edge of a-Si:H may be derived from the effect of site disorder on the zone center direct gap of c-Si.

Temperature dependence of the surface reactivity of SiH3 radicals and the surface silicon hydride composition during amorphous silicon growth

2003 ◽  
Vol 547 (3) ◽  
pp. L865-L870 ◽  
Author(s):  
W.M.M. Kessels ◽  
J.P.M. Hoefnagels ◽  
P.J. van den Oever ◽  
Y. Barrell ◽  
M.C.M. van de Sanden
Keyword(s):  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Surface Reactivity ◽  
Silicon Hydride ◽  
Silicon Growth

scholarly journals Temperature dependence of optical properties for amorphous silicon at wavelengths of 6328 and 752 nm

1993 ◽  
Vol 18 (7) ◽  
pp. 540 ◽  
Author(s):  
Oguz Yavas ◽  
Nhan Do ◽  
Andrew C. Tam ◽  
P. T. Leung ◽  
Wing P. Leung ◽  
...  
Keyword(s):  
Optical Properties ◽  
Temperature Dependence ◽  
Amorphous Silicon

In Situ Fast Temperature Measurement of Silicon Thin Films during the Excimer Laser Annealing

2006 ◽  
Vol 326-328 ◽  
pp. 195-198
Author(s):  
Seung Jae Moon
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Melting Point ◽  
Temperature Measurement ◽  
Amorphous Silicon ◽  
Laser Annealing ◽  
Crystalline Silicon ◽  
Excimer Laser Annealing ◽  
Silicon Thin Films

The formation and growth mechanism of polysilicon grains in thin films via laser annealing of amorphous silicon thin films are studied. The complete understanding of the mechanism is crucial to improve the thin film transistors used as switches in the active matrix liquid crystal displays. To understand the recrystallization mechanism, the temperature history and liquidsolid interface motion during the excimer laser annealing of 50-nm thick amorphous and polysilicon films on fused quartz substrates are intensively investigated via in-situ time-resolved thermal emission measurements, optical reflectance and transmittance measurements at near infrared wavelengths. The front transmissivity and reflectivity are measured to obtain the emissivity at the 1.52 μm wavelength of the probe IRHeNe laser to improve the accuracy of the temperature measurement. The melting point of amorphous silicon is higher than that of crystalline silicon of 1685 K by 100-150 K. This is the first direct measurement of the melting temperature of amorphous silicon thin films. It is found that melting of polysilicon occurs close to the melting point of crystalline silicon. Also the optical properties such as reflectance and transmittance are used to determine the melt duration by the detecting the difference of the optical properties of liquid silicon and solid silicon.

Temperature and bias dependence of hydrogenated amorphous silicon – crystalline silicon heterojunction capacitance: the link to band bending and band offsets

2014 ◽  
Vol 92 (7/8) ◽  
pp. 690-695 ◽  
Author(s):  
O. Maslova ◽  
A. Brézard-Oudot ◽  
M.E. Gueunier-Farret ◽  
J. Alvarez ◽  
W. Favre ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Crystalline Silicon ◽  
Inversion Layer ◽  
Hydrogenated Amorphous Silicon ◽  
Analytical Calculation ◽  
Diffusion Potential ◽  
Band Offsets ◽  
Strong Inversion ◽  
Hydrogenated Amorphous

The temperature dependence of the capacitance–voltage data (C–V–T) of very high efficiency silicon heterojunction solar cells in a wide temperature range, up to 400 K, is analyzed. We show that the temperature dependence of the capacitance exhibits an anomalously large increase with temperature that cannot be explained under the usual depletion approximation. Using the complete analytical calculation of the capacitance, where the contribution of both types of carriers is taken into account, this large increase of capacitance with temperature of p-type hydrogenated amorphous silicon – n-type crystalline silicon ((p) a-Si:H – (n) c-Si) heterojunctions observed experimentally is reproduced. This increase of the capacitance is due to a strong inversion layer at the c-Si surface, which is promoted as the temperature increases. Further we show that the temperature dependence of the 1/C2 versus applied reverse voltage (Va) plot is as well strongly affected by the strong inversion layer at the c-Si surface. Consequently, the intercept of the linear extrapolation of 1/C2 versus Va with the voltage axis (Vint) differs significantly from the total diffusion potential predicted by depletion capacitance theory. These underestimated values of the total diffusion potential can consequently lead to erroneous estimation of the band offsets. The temperature dependence of Vint is considerably enhanced for the case of the full analytical calculation when compared with the depletion approximation approach. These data, obtained directly on the final solar cell device, thus confirm the existence of a surface strong inversion layer that was previously revealed by measurements performed by other techniques on dedicated or precursor devices, allowing one to get information on the band diagram and the heterointerface.

MODELS OF PARACRYSTALLINE SILICON WITH A DEFECT-FREE BANDGAP

2001 ◽  
Vol 15 (24n25) ◽  
pp. 3253-3257 ◽  
Author(s):  
S. M. NAKHMANSON ◽  
N. MOUSSEAU ◽  
G. T. BARKEMA ◽  
P. M. VOYLES ◽  
D. A. DRABOLD
Keyword(s):  
Molecular Dynamics ◽  
Optical Properties ◽  
Amorphous Silicon ◽  
Crystalline Phase ◽  
Crystalline Silicon ◽  
New Method ◽  
Random Networks ◽  
Vibrational Properties ◽  
Switching Method ◽  
Silicon Based

Recently there have been attempts to create physically realistic models for para/poly-crystalline silicon (containing randomly oriented c-Si grains embedded in a disordered matrix) by means of empirical molecular dynamics. These models demonstrate acceptable geometrical and vibrational properties but fail to reproduce the correct electronic bandgap due to the presence of numerous "frozen-in" coordination defects. We propose a new procedure for the preparation of more realistic models of paracrystalline silicon based on a modification of the bond-switching method of Wooten, Winer and Weaire. Our new method allows us to create interfaces between the crystalline and disordered phases of Si with no coordination defects. Models with 400, 1000, and 4000 atoms were constructed. All the models have ~10 atomic % of the crystalline phase. The two smaller models contain a single crystalline grain and the largest model contains 4 randomly oriented grains. Our models show good geometrical and vibrational properties compared to good continuous random networks models of a-Si and also display excellent optical properties, correctly reproducing the electronic bandgap of amorphous silicon.

Comparison of the Optical Cross Section for the Si Dangling Bond in a- Si:H and At the c - Si/SiO2 Interface

1985 ◽  
Vol 46 ◽  
Author(s):  
W. B. Jackson ◽  
N. M. Johnson
Keyword(s):  
Optical Properties ◽  
Matrix Element ◽  
Amorphous Silicon ◽  
Cross Section ◽  
Hydrogenated Amorphous Silicon ◽  
Optical Measurements ◽  
Dipole Matrix Element ◽  
Dangling Bond ◽  
Optical Cross Section ◽  
Hydrogenated Amorphous

AbstractThe optical properties of the trivalent silicon dangling bond defect in hydrogenated amorphous silicon and at the Si/SiO2 interface are compared. While both defects give rise to ambipolar deep levels within the gap, significant differences in the optical properties between the two systems are found. The absorption in a-Si:H is significantly stronger and is dominated by a transition from the defect to the conduction band while the absorption at the interface is dominated by hole emission. The average dipole matrix element squared is roughly independent of energy in both systems with a magnitude of ∼30Å2. Implications of these results for optical measurements in other silicon systems are discussed.

Sign in / Sign up

Export Citation Format

Share Document