Charge transport in nanocrystalline germanium/hydrogenated amorphous silicon mixed-phase thin films

2013 ◽  
Vol 1536 ◽  
pp. 195-200 ◽  
Author(s):  
Kent E. Bodurtha ◽  
J. Kakalios
Keyword(s):  
Thin Films ◽  
Charge Transport ◽  
Amorphous Silicon ◽  
Channel Model ◽  
Hydrogenated Amorphous Silicon ◽  
Mixed Phase ◽  
Crystal Fraction ◽  
Germanium Nanocrystals ◽  
P Type ◽  
Hydrogenated Amorphous

ABSTRACTMixed phase thin films consisting of hydrogenated amorphous silicon (a-Si:H) in which germanium nanocrystals (nc-Ge) are embedded have been synthesized using a dual-chamber co-deposition system. Raman spectroscopy and x-ray diffraction measurements confirm the presence of 4 - 4.5 nm diameter nc-Ge homogenously embedded within the a-Si:H matrix. The conductivity and thermopower are studied as the germanium crystal fraction XGe is systematically increased. For XGe < 10%, the thermopower is n-type (as in undoped a-Si:H) while for XGe > 25% p-type transport is observed. For films with 10 < XGe < 25% the thermopower shifts from p-type to n-type as the temperature is increased. This transition is faster than expected from a standard two-channel model for charge transport.

Electronic Transport in Co-deposited Hydrogenated Amorphous/Nanocrystalline Thin Films

2008 ◽  
Vol 1066 ◽  
Author(s):  
Y. Adjallah ◽  
C. Blackwell ◽  
C. Anderson ◽  
U. Kortshagen ◽  
J. Kakalios
Keyword(s):  
Thin Films ◽  
Amorphous Silicon ◽  
Volume Fraction ◽  
Crystalline Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Nanocrystalline Silicon ◽  
Dark Conductivity ◽  
Mixed Phase ◽  
Bonding Structure ◽  
Hydrogenated Amorphous

ABSTRACTMixed-phase hydrogenated amorphous silicon thin films containing nanocrystalline silicon inclusions have been synthesized in a dual chamber co-deposition system. A PECVD deposition system produces small crystalline silicon particles (3-5 nm diameter) in a flow-through reactor, and injects these particles into a separate capacitively-coupled plasma chamber in which hydrogenated amorphous silicon is deposited. Raman spectroscopy is used to determine the volume fraction of nanocrystals in the mixed phase thin films, while infra-red spectroscopy characterizes the hydrogen bonding structure as a function of nanocrystalline concentration. At a moderate concentration of 5 nm silicon crystallites, the dark conductivity and photoconductivity are consistently found to be higher than in mixed phase films with either lower or higher densities of nanocrystalline inclusions.

Effect of Nitrogen Doping on the Structure and Optical Properties of N-Type Hydrogenated Amorphous Silicon Thin Films

2011 ◽  
Vol 383-390 ◽  
pp. 6980-6985
Author(s):  
Mao Yang Wu ◽  
Wei Li ◽  
Jun Wei Fu ◽  
Yi Jiao Qiu ◽  
Ya Dong Jiang
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Amorphous Silicon ◽  
Photoelectron Spectroscopy ◽  
Gas Flow ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Silicon Thin Films ◽  
Frequency Plasma ◽  
Hydrogenated Amorphous

Hydrogenated amorphous silicon (a-Si:H) thin films doped with both Phosphor and Nitrogen are deposited by ratio frequency plasma enhanced chemical vapor deposition (PECVD). The effect of gas flow rate of ammonia (FrNH3) on the composition, microstructure and optical properties of the films has been investigated by X-ray photoelectron spectroscopy, Raman spectroscopy and ellipsometric spectra, respectively. The results show that with the increase of FrNH3, Si-N bonds appear while the short-range order deteriorate in the films. Besides, the optical properties of N-doped n-type a-Si:H thin films can be easily controlled in a PECVD system.

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