Investigation of metastability and instability effects on the minority carrier transport properties of microcrystalline silicon thin films by using the steady-state photocarrier grating technique

2014 ◽  
Vol 92 (7/8) ◽  
pp. 763-767 ◽  
Author(s):  
Hamza Cansever ◽  
Mehmet Günes ◽  
Gökhan Yilmaz ◽  
H. Muzaffer Sagban ◽  
Vladimir Smirnov ◽  
...  
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Steady State ◽  
Minority Carrier ◽  
Crystalline Silicon ◽  
Inert Gases ◽  
Microcrystalline Silicon ◽  
Gas Treatment ◽  
Annealed State ◽  
Silicon Thin Films

Metastability effects in hydrogenated microcrystalline silicon thin films due to air, high purity nitrogen, helium, argon, and oxygen were investigated using temperature-dependent dark conductivity, photoconductivity, and steady-state photocarrier grating methods. It was found that short-term air, nitrogen, and inert gases caused a small reversible increase of σDark and σphoto within a factor of two, but they did not affect the minority carrier μτ-products significantly. These changes are partially reduced by vacuum treatment and completely reduced after heat treatment at 430 K. However, oxygen gas treatment at 80 °C resulted in more than an order of magnitude increase in both σDark and σphoto and an increase in the diffusion length, LD, by 50% from that of the annealed-state value in highly crystalline samples, while no significant metastability is detected in amorphous and low crystalline silicon thin films. A following heat treatment partially recovers both σDark and σphoto to their annealed-state values, while LD decreases only slightly. Such increase in the LD values could be due to a decrease in the density of recombination centers for holes below the Fermi level, which may be related to passivation of defects by oxygen on the surface of crystalline grains.

Investigation of meta- and in-stability effects in hydrogenated microcrystalline silicon thin films by the steady-state measurement methods

2014 ◽  
Vol 92 (7/8) ◽  
pp. 768-773 ◽  
Author(s):  
Mehmet Günes ◽  
Hamza Cansever ◽  
Gökhan Yilmaz ◽  
Muzaffer H. Sagban ◽  
Vladimir Smirnov ◽  
...  
Keyword(s):  
Thin Films ◽  
Steady State ◽  
High Purity ◽  
Volume Fraction ◽  
Silicon Film ◽  
Dark Conductivity ◽  
Deionized Water ◽  
Microcrystalline Silicon ◽  
Steady State Condition ◽  
Silicon Thin Films

Metastability effects because of atmospheric exposure, high purity gasses, and deionized water in hydrogenated microcrystalline silicon thin films with different crystalline volume fractions were studied using well accepted steady-state characterization methods of dark conductivity, steady-state photoconductivity, steady-state photocarrier grating (SSPG) and dual beam photoconductivity (DBP) methods. A standard measurement procedure has been established before using the steady state methods, in which a steady state condition of dark conductivity was established by monitoring the time dependence of dark conductivity. Samples deposited on smooth glass and rough glass substrates exhibit similar reversible and irreversible changes in the properties of microcrystalline silicon film. A reliable correlation of reversible and irreversible changes indicate that dark conductivity and photoconductivity values increase, sub-bandgap absorption spectrum obtained from DBP method decrease and correspondingly minority carrier diffusion lengths obtained from the SSPG method increase in the metastable state in various amount for microcrystalline films with crystalline volume fraction, [Formula: see text] > 0.30. Amorphous silicon and microcrystalline silicon films with [Formula: see text] < 0.30 do not show detectable metastable changes as samples exposed to atmospheric condition as well as high purity oxygen gas and deionized water.

The Precipitation of Si in AlCuSi Thin Films

1973 ◽  
Vol 31 ◽  
pp. 34-35 ◽  
Author(s):  
R. M. Anderson
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Heat Treatment ◽  
Solid Solution ◽  
Integrated Circuit ◽  
Copper Film ◽  
Solution Concentration ◽  
X Ray ◽  
Silicon Thin Films ◽  
Before And After

Aluminum-copper-silicon thin films have been considered as an interconnection metallurgy for integrated circuit applications. Various schemes have been proposed to incorporate small percent-ages of silicon into films that typically contain two to five percent copper. We undertook a study of the total effect of silicon on the aluminum copper film as revealed by transmission electron microscopy, scanning electron microscopy, x-ray diffraction and ion microprobe techniques as a function of the various deposition methods.X-ray investigations noted a change in solid solution concentration as a function of Si content before and after heat-treatment. The amount of solid solution in the Al increased with heat-treatment for films with ≥2% silicon and decreased for films <2% silicon.

Crystallization of Amorphous Silicon Thin Films by Microwave Heating

2014 ◽  
Vol 1666 ◽  
Author(s):  
Tomohiko Nakamura ◽  
Shinya Yoshidomi ◽  
Masahiko Hasumi ◽  
Toshiyuki Sameshima ◽  
Tomohisa Mizuno
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Amorphous Silicon ◽  
Microwave Heating ◽  
Volume Ratio ◽  
Heated Sample ◽  
Silicon Thin Films ◽  
Scattering Spectra ◽  
Raman Scattering Spectra ◽  
Si Films

ABSTRACTWe report crystallization of amorphous silicon (a-Si) thin films and improvement of thin film transistors (TFTs) characteristics using 2.45 GHz microwave heating assisted with carbon powders. Undoped 50-nm-thick a-Si films were formed on quartz substrates and heated by microwave irradiation for 2, 3, and 4 min. Raman scattering spectra revealed that the crystalline volume ratio increased to 0.42 for the 4-min heated sample. The dark and photo electrical conductivities measured by Air mass 1.5 at 100 mW/cm2 were 2.6x10-6 and 5.2x10-6 S/cm in the case of 4-min microwave heating followed by 1.3x106-Pa-H2O vapor heat treatment at 260°C for 3 h. N channel polycrystalline silicon TFTs characteristics were improved by the combination of microwave heating with high-pressure H2O vapor heat treatment. The threshold voltage decreased from 5.3 to 4.2 V and the effective carrier mobility increased from 18 to 25 cm2/Vs.

Effect of silane/hydrogen ratio on microcrystalline silicon thin films by remote inductively coupled plasma

2013 ◽  
Vol 113 (20) ◽  
pp. 203505 ◽  
Author(s):  
Y. N. Guo ◽  
D. Y. Wei ◽  
S. Q. Xiao ◽  
S. Y. Huang ◽  
H. P. Zhou ◽  
...  
Keyword(s):  
Thin Films ◽  
Inductively Coupled Plasma ◽  
Microcrystalline Silicon ◽  
Inductively Coupled ◽  
Silicon Thin Films

Quantitative photopyroelectric out-of-phase spectroscopy of amorphous silicon thin films deposited on crystalline silicon

1991 ◽  
Vol 69 (3-4) ◽  
pp. 317-323 ◽  
Author(s):  
Constantinos Christofides ◽  
Andreas Mandelis ◽  
Albert Engel ◽  
Michel Bisson ◽  
Gord Harling
Keyword(s):  
Thin Films ◽  
Optical Absorption ◽  
Absorption Coefficient ◽  
Dynamic Range ◽  
Crystalline Silicon ◽  
Optical Absorption Coefficient ◽  
Si Substrates ◽  
Silicon Thin Films ◽  
Background Compensation

A photopyroelectric spectrometer with real-time and(or) self-normalization capability was used for both conventional transmission and thermal-wave spectroscopic measurements of amorphous Si thin films, deposited on crystalline Si substrates. Optical-absorption-coefficient spectra were obtained from these measurements and the superior dynamic range of the out-of-phase (quadrature) photopyroelectric signal was established as the preferred measurement method, owing to its zero-background compensation capability. An extension of a photopyroelectric theoretical model was established and successfully tested in the determination of the optical absorption coefficient and the thermal diffusivity of the sample under investigation. Instrumental sensitivity limits of βt ≈ 5 × 10−3 were demonstrated.

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