On the Compensation Mechanism of Amorphous Silicon Films: Study of Stability

1997 ◽  
Vol 467 ◽  
Author(s):  
D. Caputo ◽  
G. De Cesare ◽  
F. Palma ◽  
M. Tucci ◽  
C. Minarini ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Gas Phase ◽  
Formation Mechanism ◽  
Boron Concentration ◽  
Defect Density ◽  
Silicon Films ◽  
Compensation Mechanism ◽  
Relevant Result ◽  
Wide Range

ABSTRACTWe investigated a-Si:H compensated materials deposited over a wide range of gas dopant concentrations, from 0.125 ppm up to 103 ppm.We achieved compensation for different ratio in the gas phase of diborane and phosphine, depending on their concentration. As a relevant result, we found that at constant boron concentration compensation occurs by using two different values of phosphine flow. This behavior can be described by a change of formation mechanism involving active dopants, defects and boron-phosphorus complex, that occurs in a different way depending on the dopant concentrations.The two compensation regimes are evidenced also by a different behavior under light soaking. Furthermore we found that photocurrent evolution under illumination is determined by two concurrent mechanisms: activation of dopant species and increase of defect density.

HYDROGEN PROFILING IN GAS PHASE DOPED AND ION IMPLANTED AMORPHOUS SILICON FILMS

1981 ◽  
Vol 42 (C4) ◽  
pp. C4-779-C4-782 ◽  
Author(s):  
F. J. Demond ◽  
G. Müller ◽  
H. Damjantschitsch ◽  
H. Mannsperger ◽  
S. Kalbitzer ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Gas Phase ◽  
Silicon Films ◽  
Ion Implanted

On the relation between defect density and dopant concentration in amorphous silicon films

2000 ◽  
Vol 266-269 ◽  
pp. 565-568 ◽  
Author(s):  
Domenico Caputo ◽  
Giampiero de Cesare ◽  
Fernanda Irrera ◽  
Augusto Nascetti ◽  
Fabrizio Palma
Keyword(s):  
Amorphous Silicon ◽  
Dopant Concentration ◽  
Defect Density ◽  
Silicon Films

Dependence of Steady-State Defect Density in Hydrogenated Amorphous Silicon on Carrier Generation Rate Studied Over a Wide Range

1993 ◽  
Vol 297 ◽  
Author(s):  
Nobuhiro Hata ◽  
Gautam Ganguly ◽  
Akihisa Matsuda
Keyword(s):  
Steady State ◽  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Continuous Light ◽  
Effective Rate ◽  
Defect States ◽  
Carrier Generation ◽  
Wide Range ◽  
Hydrogenated Amorphous

Measurements of the steady-state defect density (Nst) in hydrogenated amorphous silicon under illumination of pulse-laser light, as well as of continuous light, were carried out; and the dependence of Nst on the effective rate of carrier generation (G) is presented. The values of G ranged from 8 x 1021 to 2.4 × 1023 cm-3 s-1, while the illumination temperature was kept at 30 °C or at 105 °C. The results showed trends of Nst increasing with G similarly to the trends in the literature, but covered a higher and wider G range, and fitted a defect model which assumes a limited number of possible defect states.

Resistless Patterning of Hydrogenated Amorphous Silicon Films

1999 ◽  
Vol 557 ◽  
Author(s):  
Russell E. Hollingsworth ◽  
Mary K. Hemdon ◽  
Reuben T. Collins ◽  
J.D. Benson ◽  
J.H. Dinan ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Pattern Generation ◽  
Silicon Films ◽  
Contact Printing ◽  
Direct Patterning ◽  
Projection Lithography ◽  
Wide Range ◽  
Hydrogenated Amorphous

AbstractPractical methods for directly patterning hydrogenated amorphous silicon (a-Si:H) films have been developed. Direct patterning involves selectively oxidizing the hydrogen passivated a-Si:H surface or laser crystallization of the bulk. The oxide or polycrystalline layer formed in this way then becomes a mask for subsequent hydrogen plasma etching. Methods for selective oxidation of the a-Si:H surface have been extensively studied. Examination of the pattern generation threshold dose for excitation wavelengths from 248 to 633nm provides indirect evidence for electron-hole recombination breaking of the silicon-hydrogen bond. An additional hydrogen removal mechanism was observed whereby simple proximity of a tapered fiber optic probe less than 30nm from the sample surface resulted in pattern generation. Patterns were generated in both intrinsic and doped a-Si:H films by several means, including contact printing with a mask aligner, in situ projection lithography with an excimer laser, and direct writing with a near-field scanning optical microscope (NSOM). Direct patterning of a-Si:H films has a wide range of potential applications. We have demonstrated a-Si:H as an in situ photoresist material for patterning HgCdTe infrared detector arrays with all process steps done in vacuum. We have also demonstrated 100nm line widths using NSOM writing with a photolithography goal. Direct patterning of a-Si:H could simplify the manufacturing of thin film transistors, or other devices that require patterned silicon films.

Intrinsic Stacking Interactions of Natural and Artificial Nucleobases

2019 ◽  
Author(s):  
Drew P. Harding ◽  
Laura J. Kingsley ◽  
Glen Spraggon ◽  
Steven Wheeler
Keyword(s):  
Gas Phase ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Molecular Descriptors ◽  
Stacking Interactions ◽  
Interaction Energies ◽  
Functional Theory ◽  
Binding Partner ◽  
Heavy Atoms ◽  
Wide Range

The intrinsic (gas-phase) stacking energies of natural and artificial nucleobases were explored using density functional theory (DFT) and correlated ab initio methods. Ranking the stacking strength of natural nucleobase dimers revealed a preference in binding partner similar to that seen from experiments, namely G > C > A > T > U. Decomposition of these interaction energies using symmetry-adapted perturbation theory (SAPT) showed that these dispersion dominated interactions are modulated by electrostatics. Artificial nucleobases showed a similar stacking preference for natural nucleobases and were also modulated by electrostatic interactions. A robust predictive multivariate model was developed that quantitively predicts the maximum stacking interaction between natural and a wide range of artificial nucleobases using molecular descriptors based on computed electrostatic potentials (ESPs) and the number of heavy atoms. This model should find utility in designing artificial nucleobase analogs that exhibit stacking interactions comparable to those of natural nucleobases. Further analysis of the descriptors in this model unveil the origin of superior stacking abilities of certain nucleobases, including cytosine and guanine.

Sign in / Sign up

Export Citation Format

Share Document