NMR Investigation of the Local Dopant-Hydrogen Configuration in Amorphous Silicon

1987 ◽  
Vol 95 ◽  
Author(s):  
S. E. Ready ◽  
J. B. Boyce
Keyword(s):  
Amorphous Silicon ◽  
Plasma Deposition ◽  
Spin Echo ◽  
Double Resonance ◽  
Structural Units ◽  
Long Term Stability ◽  
Heavily Doped ◽  
P Type ◽  
Hydrogenated Amorphous

AbstractHydrogen's role in the doping efficiency and long term stability of hydrogenated amorphous silicon is not well understood. The introduction of dopants has been observed to cause an increase in the deposition rate and in the formation of dangling bonds. We have performed NMR spin echo double resonance measurements on heavily doped amorphous silicon samples prepared via plasma deposition in order to ascertain the dopanthydrogen structural units. The resulting dopant concentrations were 2.0 and 0.5 at. % boron and/or phosphorus in compensated and singly doped material respectively. Our results indicate no direct dopant-hydrogen bonding in the compensated or n-type samples. However, in the p-type material the data indicate that approximately 40% of the boron atoms are directly bonded to a hydrogen.

Reliability of Ohmic Contacts for AlGaAs/GaAs HBTs

1990 ◽  
Vol 184 ◽  
Author(s):  
G. S. Jackson ◽  
E. Tong ◽  
P. Saledas ◽  
T. E. Kazior ◽  
R. Sprague ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Contact Resistance ◽  
Ohmic Contacts ◽  
Ion Beam ◽  
Sintering Process ◽  
Electrical Stability ◽  
Long Term Stability ◽  
Heavily Doped ◽  
P Type

ABSTRACTThe reliability of ohmic contacts to thin, heavily doped layers of GaAs is investigated. Pd/Ge/Au contacts to n-type GaAs display excellent electrical stability over extended periods of thermal stress. The contact resistance stays below 0.50Ω-mim during a 2500h, 280°C bake. Reactive ion beam assisted evaporation of Ti with N forms TiN which is introduced as a barrier layer in Pt/TiN/Ti/Au contacts to a thin p+ layer. The TiN layer allows greater process latitude in the sintering process and improves long term stability of the ohmic contact. The microstructure of the p-type contacts is examined with TEM and Auger profiling at different instances of the 2500h, 280°C bake and compared to the contact resistance measurements.

Reliability of Ohmic Contacts for AlGaAs/GaAs HBTs

1990 ◽  
Vol 181 ◽  
Author(s):  
G. S. Jackson ◽  
E. Tong ◽  
P. Saledas ◽  
T. E. Kazior ◽  
R. Sprague ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Contact Resistance ◽  
Ohmic Contacts ◽  
Ion Beam ◽  
Sintering Process ◽  
Electrical Stability ◽  
Long Term Stability ◽  
Heavily Doped ◽  
P Type

ABSTRACTThe reliability of ohmic contacts to thin, heavily doped layers of GaAs is investigated. Pd/Ge/Au contacts to n-type GaAs display excellent electrical stability over extended periods of thermal stress. The contact resistance stays below 0.5Ω-mm during a 2500h, 280°C bake. Reactive ion beam assisted evaporation of Ti with N forms TiN which is introduced as a barrier layer in Pt/TiN/Ti/Au contacts to a thin p+ layer. The TiN layer allows greater process latitude in the sintering process and improves long term stability of the ohmic contact. The microstructure of the p-type contacts is examined with TEM and Auger profiling at different instances of the 2500h, 280°C bake and compared to the contact resistance measurements.

Use of Transparent Conductive Oxide Materials with Low Indices of Refraction in Amorphous Silicon-Based Solar Cell Technology

2005 ◽  
Vol 862 ◽  
Author(s):  
Scott J. Jones ◽  
Joachim Doehler ◽  
Tongyu Liu ◽  
David Tsu ◽  
Jeff Steele ◽  
...  
Keyword(s):  
Solar Cell ◽  
Amorphous Silicon ◽  
Transparent Conductive Oxide ◽  
Open Circuit ◽  
Long Term Stability ◽  
Back Reflectors ◽  
Stability Issues ◽  
Silicon Based ◽  
Solar Cell Technology

AbstractNew types of transparent conductive oxides with low indices of refraction have been developed for use in optical stacks for the amorphous silicon (a-Si) solar cell and other thin film applications. The alloys are ZnO based with Si and MgF added to reduce the index of the materials through the creation of SiO2 or MgF2, with n=1.3-1.4, or the addition of voids in the materials. Alloys with 12-14% Si or Mg have indices of refraction at λ=800nm between 1.6 and 1.7. These materials are presently being used in optical stacks to enhance light scattering by Al/multi-layer/ZnO back reflectors in a-Si based solar cells to increase light absorption in the semiconductor layers and increase open circuit currents and boost device efficiencies. In contrast to Ag/ZnO back reflectors which have long term stability issues due to electromigration of Ag, these Al based back reflectors should be stable and usable in manufactured PV products. In this manuscript, structural properties for the materials will be reported as well as the performance of solar cell devices made using these new types of materials.

1/f Noise in Mott Variable Range Hopping Conduction in p-type Amorphous Silicon

2015 ◽  
Vol 1770 ◽  
pp. 25-30 ◽  
Author(s):  
V.C. Lopes ◽  
A.J. Syllaios ◽  
D. Whitfield ◽  
K. Shrestha ◽  
C.L. Littler
Keyword(s):  
Electrical Conductivity ◽  
Amorphous Silicon ◽  
Chemical Vapor ◽  
Variable Range Hopping ◽  
Temperature Dependent ◽  
Noise Component ◽  
Variable Range ◽  
Noise Measurements ◽  
P Type ◽  
Hydrogenated Amorphous

ABSTRACTWe report on electrical conductivity and noise measurements made on p-type hydrogenated amorphous silicon (a-Si:H) thin films prepared by Plasma Enhanced Chemical Vapor Deposition (PECVD). The temperature dependent electrical conductivity can be described by the Mott Variable Range Hopping mechanism. The noise at temperatures lower than ∼ 400K is dominated by a 1/f component which follows the Hooge model and correlates with the Mott conductivity. At high temperatures there is an appreciable G-R noise component.

scholarly journals A Room Temperature Gas Sensor Based on Sulfonated SWCNTs for the Detection of NO and NO2

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1116 ◽  
Author(s):  
Eusebiu Ionete ◽  
Stefan Spiridon ◽  
Bogdan Monea ◽  
Elena Stratulat
Keyword(s):  
Room Temperature ◽  
Gas Sensing ◽  
Electrical Response ◽  
Long Term Stability ◽  
Sensing Applications ◽  
Specific Configuration ◽  
P Type ◽  
Walled Carbon Nanotubes ◽  
Type Response

The electrical response of sulfonated single-walled carbon nanotubes (SWCNTs) to NO and NO2, for gas sensing applications, at room temperature, is reported in this work. A specific configuration based on SWCNT deposition between double pair configuration gold electrodes, supported on a substrate, was considered for the sensing device; employed characterization technique where FTIR and SEM. The experimental results showed a p-type response of the sulfonated SWCNTs, with decrease in resistance, under exposure to NO gas (40–200 ppb) and NO2 (40–200 ppb). Also, the sensor responses to successive exposures at NO2 800 ppb together with investigation of long term stability, at 485 ppb for NO, are reported. The reaction mechanism in case of NO and NO2 detection with sulfonated SWCNTs is presented.

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