Charge Transport in the Transition From Hydrogenated Amorphous Silicon to Microcrystalline Silicon

1999 ◽  
Vol 557 ◽  
Author(s):  
A. Kattwinkel ◽  
R. Braunstein ◽  
G. Sun ◽  
Qi Wang
Keyword(s):  
Electronic Transport ◽  
Amorphous State ◽  
Chemical Vapor ◽  
Charge Carriers ◽  
Hot Wire ◽  
Microcrystalline Silicon ◽  
Potential Fluctuations ◽  
Scattering Centers ◽  
Improved Stability ◽  
Hydrogenated Amorphous

AbstractThe electronic transport properties of a series of samples prepared by hot-wire chemical vapor deposition with a transition from a-Si:H to μc-Si:H were measured applying the photoconductive frequency mixing technique. We found both improved stability against light-soaking and different values for the photomixing electron lifetime and mobility close to the onset of microcrystallinity as compared to the amorphous state. In particular, the mobility-lifetime product of charge carriers in some of the μc-Si:H samples turns out to lie about two orders of magnitude higher than that of a-Si:H films. The mobility on the other hand, is shown rather to decrease in the transition to the μc-region. Additional measurements of the range and the depth of long range potential fluctuations yield a possible explanation for our results in that grain boundaries may serve as scattering centers and barriers against recombination.

Increase of Hydrogen-Radical Density and Improvement of The Crystalline Volume Fraction of Microcrystalline Silicon Films Prepared by Hot-Wire Assisted Pecvd Method

2000 ◽  
Vol 609 ◽  
Author(s):  
Norimitsu Yoshida ◽  
Takashi Itoh ◽  
Hiroki Inouchi ◽  
Hidekuni Harada ◽  
Katsuhiko Inagaki ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Chemical Vapor ◽  
Rf Plasma ◽  
Hot Wire ◽  
Dilution Ratio ◽  
Microcrystalline Silicon ◽  
Hydrogen Dilution ◽  
Hydrogen Radical ◽  
Hydrogen Radicals ◽  
Hydrogenated Amorphous

ABSTRACTHigher crystalline Si volume fractions in hydrogenated microcrystalline silicon ( µc-Si:H) films have been achieved by the hot-wire assisted plasma enhanced chemical vapor deposition (HWA-PECVD) method compared with those in films by conventional PECVD. µc-Si:H films can also be prepared by HWA-PECVD under typical conditions used for preparing hydrogenated amorphous silicon (a-Si:H) films by PECVD, in which the hydrogen-dilution ratio (H2 / SiH4) is ∼ 10. The hot wire seems to produce hydrogen radicals. As a result, the HWA- PECVD method can control hydrogen-radical densities in the RF plasma, and this method can also control the ratio of hydrogen coverage at the surface of the film.

Light-Induced Effects on Fluorinated Amorphous and Microcrystalline Silicon Films

1996 ◽  
Vol 420 ◽  
Author(s):  
Hong-Seok Choi ◽  
Keun-Ho Jang ◽  
Jhun-Suk Yoo ◽  
Min-Koo Han
Keyword(s):  
Band Gap ◽  
Vapor Deposition ◽  
Optical Band Gap ◽  
Silicon Film ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Rf Plasma ◽  
Microcrystalline Silicon ◽  
Amorphous Silicon Film ◽  
Hydrogenated Amorphous

AbstractThe fluorinated amorphous and microcrystalline silicon (a,μc-Si:H;F) films have been prepared by rf plasma enhanced chemical vapor deposition (PECVD) with SiH 4 and SiF 4 gas mixtures. The stretching Si-O (1085 cm-1) and SiH2 (2100 cm-1) bands estimated from infrared (IR) spectroscope data have related to the evolution of crystallinity and the optical band gap was shifted by introducing Si-O bonds. The sub-band gap absorption coefficient in a,μc-Si:H;F films was about one order lower than that in hydrogenated amorphous silicon film (a-Si:H). The subband gap absorption in a-Si:H;F film was comparable to that in tic-Si:H;F films. The lightinduced degradation of a,μc-Si:H;F films were also suppressed.

Stress in Hydrogenated Microcrystalline Silicon Thin Films

1999 ◽  
Vol 557 ◽  
Author(s):  
D. Peiró ◽  
C. Voz ◽  
J. Bertomeu ◽  
J. Andreu ◽  
E. Martínez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Hot Wire ◽  
X Ray Diffraction ◽  
Microcrystalline Silicon ◽  
X Ray ◽  
Silicon Thin Films ◽  
Abrupt Changes

AbstractHydrogenated microcrystalline silicon films have been obtained by hot-wire chemical vapor deposition (HWCVD) in a silane and hydrogen mixture at low pressure (<5 × 10-2 mbar). The structure of the samples and the residual stress were characterised by X- ray diffraction (XRD). Raman spectroscopy was used to estimate the volume fraction of the crystalline phase, which is in the range of 86 % to 98%. The stress values range between 150 and -140 MPa. The mechanical properties were studied by nanoindentation. Unlike monocrystalline wafers, there is no evidence of abrupt changes in the force-penetration plot, which have been attributed to a pressure-induced phase transition. The hardness was 12.5 GPa for the best samples, which is close to that obtained for silicon wafers.

Photoluminescence in B-doped μc-Si:H

1992 ◽  
Vol 283 ◽  
Author(s):  
S. Q. Gu ◽  
J. M. Viner ◽  
P. C. Taylor ◽  
M. J. Williams ◽  
W. A. Turner ◽  
...  
Keyword(s):  
Broad Band ◽  
Chemical Vapor ◽  
Boron Doping ◽  
Dark Conductivity ◽  
Microcrystalline Silicon ◽  
Band Tail ◽  
Pl Spectra ◽  
Photothermal Deflection Spectroscopy ◽  
Photothermal Deflection ◽  
Hydrogenated Amorphous

ABSTRACTPhotoluminescence (PL) has been investigated in hydrogenated microcrystalline silicon (μc-Si:H) samples as a function of boron doping for films prepared by remote plasma enhanced chemical vapor deposition. When the dark conductivity a is below about 10-5 S/cm, the PL spectra exhibit a shape which is close to that of the so-called band tail PL in undoped hydrogenated amorphous silicon (a-Si:H) at 77 K. When a increases, the PL intensity decreases at 77 K. For samples with a on the order of 10-3 S/cm, the PL spectra show only a narrow, low energy PL band which peaks around 0.8–0.9 eV. In these samples, the PL at higher energy is essentially not observable. This trend is similar to that which occurs in doped a-Si:H. However, for higher doping levels (σ ∼ 1 S/cm) the PL in μc-Si:H, although very weak, exhibits a broad band which contains intensity at higher energies. The absorption spectra in these samples, as measured by photothermal deflection spectroscopy (PDS), show the same relationships with the corresponding PL spectra as do the PDS spectra in doped a-Si:H.

High Mobility a-Si:H TFT Fabricated by Hot Wire Chemical Vapor Deposition

2010 ◽  
Vol 1245 ◽  
Author(s):  
Chun-Yuan Hsueh ◽  
Chieh-Hung Yang ◽  
Si-Chen Lee
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Field Effect ◽  
High Mobility ◽  
Chemical Vapor ◽  
Field Effect Mobility ◽  
Hot Wire ◽  
Low Threshold ◽  
Hydrogenated Amorphous ◽  
Very High

AbstractThe hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) having a very high field-effect mobility of 1.76 cm2/V-s and a low threshold voltage of 2.43 V have been fabricated successfully using the hot wire chemical vapor deposition (HWCVD).

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