Properties and Local Structure of Plasma-Deposited Amorphous Silicon-Carbon Alloys

1986 ◽  
Vol 70 ◽  
Author(s):  
W. C. Mohr ◽  
C. C. Tsai ◽  
R. A. Street
Keyword(s):  
Substrate Temperature ◽  
Amorphous Silicon ◽  
Gas Phase ◽  
Vacuum Annealing ◽  
Dangling Bond ◽  
Bond Density ◽  
Silicon Carbon ◽  
Back Bonding ◽  
Hydrogenated Amorphous ◽  
Gas Ratio

ABSTRACTHydrogenated amorphous silicon-carbon alloy films were plasma-deposited from metnane and silane, varying gas ratio, R.F. power and substrate temperature. Carbon addition increases the optical gap, but also raises the dangling bond density while decreasing conductivity. Low C alloys can be gas-phase doped both p and n type. In the IR spectra the various Si-C stretching modes observed between 650 and 780 cm-1 are explained by back bonding variations. A tentative method of assigning this shift to back bonding of C to the Si is given. A distribution of modes is observed for all alloys, with each mode appearing even at 2% C. The distribution is sensitive to substrate temperature, but is stable after vacuum annealing to 400°C.

Changes in hydrogenated amorphous silicon upon extensive light-soaking at elevated temperature

2001 ◽  
Vol 664 ◽  
Author(s):  
N. Hata ◽  
C. M. Fortmann ◽  
A. Matsuda
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Amorphous Silicon ◽  
High Intensity ◽  
Dangling Bond ◽  
Defect States ◽  
Silicon Thin Films ◽  
Bond Density ◽  
Hydrogenated Amorphous ◽  
High Intensity Light

ABSTRACTPreviously a through the substrate ellipsomtery technique was used to study the high temperature dynamics of light induced reversible changes in amorphous silicon thin films [1]. Since this technique was based on above gap optical changes it is sensitive to the structural aspects of the light induced effects, differently from the below-gap absorption techniques which detect dangling-bond defect states [2-3]. It was found that high intensity light soaking at an elevated temperature causes surprising large, reversible, changes [1]. By comparing these optical changes with the changes in dangling bond concentrations probed by electronic and below gap methods, a fuller picture of temperature dependent light-induced defect creation and annealing dynamics emerges. A high temperature high intensity light soaking method is developed which reduces saturation times, decreases the saturated dangling bond density, as well as decreases the annealing activation energy. These results are discussed in terms of the coupling between network disorder and its relaxation with respect to defect concentrations at high temperature.

scholarly journals Material Parameters in a Thick Hydrogenated Amorphous Silicon Detector and their Effect on Signal Collection

1989 ◽  
Vol 149 ◽  
Author(s):  
S. Qureshi ◽  
V. Perez-Mendez ◽  
S. N. Kaplan ◽  
I. Fujieda ◽  
G. Cho
Keyword(s):  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Silicon Detector ◽  
Dangling Bond ◽  
Material Parameters ◽  
Bond Density ◽  
Transient Photoconductivity ◽  
Signal Collection ◽  
Hydrogenated Amorphous

ABSTRACTTransient photoconductivity and ESR measurements were done to relate the ionized dangling bond density and the spin density of thick hydrogenated amorphous silicon (a-Si:H) detectors. We found that only a fraction (∼30–35%) of the total defect density as measured by ESR is ionized when the detector is biased into deep depletion. The measurements on annealed samples also show that this fraction is about 0.3. An explanation based on the shift of the Fermi energy is given. The measurements show that the time dependence of relaxation is a stretched exponential.

Capacitance Studies of Light-Induced Effects in Undoped Hydrogenated Amorphous Silicon

1985 ◽  
Vol 49 ◽  
Author(s):  
K. Zellama ◽  
J.D. Cohen ◽  
J.P. Harbison
Keyword(s):  
Electrical Conductivity ◽  
Amorphous Silicon ◽  
Density Of States ◽  
Hydrogenated Amorphous Silicon ◽  
Dangling Bond ◽  
Light Saturation ◽  
Band Tail ◽  
Bond Density ◽  
Induced Changes ◽  
Hydrogenated Amorphous

AbstractThe effects of light saturation on the properties of undoped a-Si:H films were studied by a new capacitance profiling technique which can be used to directly determine changes in the dangling bond density of states near midgap. Coplanar conductivity and capacitance vs. temperature measurements save the changes in activation energies for electrical conductivity. These studies indicate that, while substantial increases in the dangling bond densities are observed for most samples, the detailed behavior of the light induced changes in these films are inconsistent with the creation of such defects by breaking weak valence band tail states.

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