Experimental Determination of the Dark Fermi Level in Hydrogenated Amorphous Silicon.

1992 ◽  
Vol 258 ◽  
Author(s):  
R.M. Dawson ◽  
S. Nag ◽  
M. Gunes ◽  
C.R. Wronski ◽  
M. Bennett ◽  
...  
Keyword(s):  
Fermi Level ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Activation Energies ◽  
Key Factors ◽  
In Series ◽  
Measured Activation ◽  
Hydrogenated Amorphous ◽  
Probe Measurements

ABSTRACTThe position of the dark fermi level in hydrogenated amorphous silicon (a-Si:H) is important in determining its electrical properties and is a key parameter in the detailed modelling of materials and devices. The activation energies of conductivities have been investigated on intrinsic a-Si:H films from various laboratories where the slopes of the Arrhenius plots have ranged from 0.27 eV to 0.87 eV. In many cases, marked differences are found between the results obtained from two and four probe measurements, highlighting the importance of the four probe configuration. Results are presented which help to explain the scatter in the measured activation energies between intrinsic films of a-Si:H. Differences in the activation energies are discussed in terms of current limiting processes which act in series with the material bulk resistance. It will be shown that the conductivity of the film and the contact are key factors in assessing whether the position of the fermi level can be accurately determined from a two contact measurement.

Mechanical Spectroscopy Study on the Light Soaking Effect on Hydrogenated Amorphous Silicon

2012 ◽  
Vol 184 ◽  
pp. 416-421 ◽  
Author(s):  
H. Mizubayashi ◽  
I. Sakata ◽  
H. Tanimoto
Keyword(s):  
Internal Friction ◽  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Wide Distribution ◽  
Activation Energies ◽  
Mechanical Spectroscopy ◽  
Induced Changes ◽  
Mild Temperature ◽  
Hydrogenated Amorphous

For hydrogenated amorphous silicon (a-Si:H) films deposited at temperatures between 423 K and 623 K (a-Si:H423Kand so on), the light-induced changes in the internal friction between 80 K and 400 K were studied. The internal friction is associated with H2motion in microvoid networks, and shows the mild temperature dependence between about 80 K and 300 K (Q-180-300K) and the almost linear increase above 300 K (Q-1>300K). BothQ-180-300KandQ-1>300Kdecrease with increasing the deposition temperature, and show the mild temperature dependence ina-Si:H623K. The white light soaking with 100 mW/cm2(WLS100and so on) below 300 K caused a change inQ-180-300Kand no changes inQ-1>300K, respectively, and the light-induced changes inQ-180-300Krecovered after annealing at 423 K. The wide distribution of activation energies for H2motions between microvoids indicate that most of neighboring microvoids are connected through windows, i.e., the microvoid networks are existing ina-Si:H, and the spatially loose or solid structures are responsible for the low or high activation energies for the H2motion between microvoids, respectively. Furthermore, the light-induced hydrogen evolution (LIHE) was observed for WLS200to WLS400in a vacuum between 400 and 500 K, resulting in the disappearance of the internal friction due to the H2motion in the microvoid network.

Determination of the Mobile-Hydrogen Charge State in Hydrogenated Amorphous Silicon

2001 ◽  
Vol 664 ◽  
Author(s):  
Brent P. Nelsona ◽  
Yueqin Xu ◽  
Robert C. Reedy ◽  
Richard S. Crandall ◽  
A. Harv Mahan ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Electric Fields ◽  
Correlation Energy ◽  
Hydrogen Charge ◽  
Hydrogenated Amorphous Silicon ◽  
Mobile Hydrogen ◽  
Almost All ◽  
Hydrogenated Amorphous ◽  
Best Fit

ABSTRACTWe find that hydrogen diffuses as H+, H0, or H- in hydrogenated amorphous silicon depending on its location within the i-layer of a p-i-n device. We annealed a set of five p-i-n devices, each with a thin deuterium-doped layer at a different location in the i-layer, and observed the D-diffusion using secondary ionmass spectrometry (SIMS). When H-diffuses in a charged state, electric fields in the device strongly influence the direction and distance of diffusion. When D is incorporated into a device near the p-layer, almost all of the D-diffusion occurs as D+, and when the D is incorporated near the n-layer, most of the D-diffusion occurs as D-. We correlate the preferential direction of D-motion at given depth within the i-layer, with the local Fermi level (as calculated by solar cell simulations), to empirically determine an effective correlation energy for mobile-H electronic transitions of 0.39 ± 0.1 eV. Using this procedure, the best fit to the data produces a disorder broadening of the transition levels of ∼0.25 eV. The midpoint between the H0/+ and the H0/- transition levels is ∼0.20 ± 0.05 eV above midgap.

Responsivity determination of a hydrogenated amorphous silicon micro-bolometer array

2011 ◽  
Author(s):  
A. Orduña-Díaz ◽  
M. Rojas-López ◽  
R. Delgado-Macuil ◽  
Alfonso Torres-Jácome ◽  
F. J. De la Hidalga-Wade ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Bolometer Array ◽  
Hydrogenated Amorphous
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