The Effect of Oxygen Contamination on the Electronic Properties of Hot-Wire CVD Amorphous Silicon Germanium Alloys

2006 ◽  
Vol 910 ◽  
Author(s):  
Shouvik Datta ◽  
J. David Cohen ◽  
Steve L. Golledge ◽  
Yueqin Xu ◽  
A. H. Mahan ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Silicon Germanium ◽  
Film Growth ◽  
Impurity Level ◽  
Oxygen Impurity ◽  
Hot Wire ◽  
Si Substrates ◽  
Oxygen Contamination ◽  
Effect Of Oxygen ◽  
High Level

AbstractA series of four a Si,Ge:H alloy samples with Ge fractions near 30 at.% were deposited by hot-wire CVD (HWCVD) using a Ta filament maintained at 1800oC. During film growth, the level of oxygen contamination was varied from less than 1019 cm−3 to roughly 5 × 1020 cm−3 using a controlled air-leak. The electronic properties of these films were then characterized using transient photocapacitance (TPC) and transient photocurrent (TPI) spectroscopy, as well as the drive-level capacitance profiling (DLCP) techniques. We observed an unexpected systematic improvement of the electronic properties of these HWCVD a Si,Ge:H with increasing oxygen impurity level, which was reflected by a decrease in the deduced Urbach energies. Comparing these with films co-deposited on stainless-steel versus p+ c-Si substrates, we found significantly better electronic properties in the latter case. Comparisons of the TPC and TPI spectra indicated a very high level of hole collection, consistent with these narrow bandtail distributions.

Electronic Properties of Improved Amorphous Silicon-Germanium Alloys Deposited by a Low Temperature Hot Wire Chemical Vapor Deposition Process

2005 ◽  
Vol 862 ◽  
Author(s):  
Shouvik Datta ◽  
J. David Cohen ◽  
Yueqin Xu ◽  
A. H. Mahan
Keyword(s):  
Chemical Vapor Deposition ◽  
Electronic Properties ◽  
Vapor Deposition ◽  
Silicon Germanium ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Alloy Sample ◽  
Hot Wire ◽  
Novel Material ◽  
Amorphous Silicon Germanium

AbstractWe report novel material properties of a series of a-Si,Ge:H alloys grown by hot-wire chemical vapor deposition under low filament temperature (˜1800°C) and low substrate temperature (˜200-300°C). These alloys exhibit significantly improved electronic properties including low defect densities and sharp band tails (Urbach energies ≤ 45meV even for Ge fractions as high as 47at.%). On the other hand, comparisons of the transient photocapacitance and transient photocurrent spectra do not indicate very efficient hole collection in these materials. We found two distinct regimes of light-induced degradation in the alloy sample with 29at.% Ge fraction, possibly corresponding to the light induced increase of Ge and Si dangling bonds, respectively.

Two-Step Capacitance Transients From an Oxygen Impurity Defect

2008 ◽  
Vol 1066 ◽  
Author(s):  
Shouvik Datta ◽  
J. David Cohen ◽  
Yueqin Xu ◽  
Howard M. Branz
Keyword(s):  
Electron Emission ◽  
Vapor Deposition ◽  
Silicon Germanium ◽  
Chemical Vapor ◽  
Oxygen Impurity ◽  
Pulse Time ◽  
Hot Wire ◽  
Impurity Defect ◽  
Amorphous Silicon Germanium ◽  
Hydrogenated Amorphous

ABSTRACTThis paper describes the study of an electron-trapping defect which underwent significant configurational relaxation in oxygen contaminated hydrogenated amorphous silicon-germanium (a-Si,Ge:H) alloys grown by hot-wire chemical vapor deposition. An unusual two-step electron emission from this relaxed defect is studied using junction-capacitance-based measurements. In this work, we monitor the recovery of the relaxed defect after filling it by photoexcited electrons and also by electrons injected with a voltage filling pulse. The dependence of the transient shape on filling pulse time is described. We have also performed experiments which clearly demonstrate that this is a bulk defect and exclude contributions from any additional blocking junctions.

Dependence of the Electronic Properties of Hot-Wire CVD Amorphous Silicon-Germanium Alloys on Oxygen Impurity Levels

2007 ◽  
Vol 989 ◽  
Author(s):  
Shouvik Datta ◽  
J. David Cohen ◽  
Yueqin Xu ◽  
A. H. Mahan ◽  
Howard M. Branz
Keyword(s):  
Amorphous Silicon ◽  
Valence Band ◽  
Silicon Germanium ◽  
Oxygen Impurity ◽  
Hot Wire ◽  
Defect Level ◽  
Related Defect ◽  
Amorphous Silicon Germanium ◽  
Oxygen Impurities ◽  
Silicon Germanium Alloys

AbstractWe report the effects of intentionally introducing up to ∼ 5×1020/cm3 oxygen impurities into hydrogenated amorphous silicon-germanium alloys (of roughly 30at.% Ge) grown by the hot-wire chemical vapor deposition (HWCVD) method. Deep defect densities determined by drive-level capacitance profiling (DLCP) indicated a modest increase with increasing oxygen content (up to a factor of 3 at the highest oxygen level). Transient photocapacitance (TPC) spectra indicated a clear spectral signature for an optical transition between the valence band and an additional defect level which is attributed to oxygen impurities. The oxygen impurity related defect transition has an optical threshold around 1.4eV above the valence band and also results in a negative contribution to the TPC signal. This initially led us to believe that the bandtail for the higher oxygen samples was much narrower than it actually is. Surprisingly, this additional oxygen related defect level appears to have only a very minor effect upon the estimated minority carrier collection fraction. The effects of light-induced degradation upon some of these oxygen contaminated samples were also examined. We infer the existence of a significant thermal barrier to explain the observed spectral signatures of this oxygen impurity defect.

Effect of oxygen impurity on thermal conduction rate of poly‐crystalline Si 3 N 4

2021 ◽  
Author(s):  
Hwan Soo Dow ◽  
Moonkyong Na ◽  
Yeon Wook Jung ◽  
Seung Geun Jo ◽  
Jung Woo Lee
Keyword(s):  
Thermal Conduction ◽  
Oxygen Impurity ◽  
Effect Of Oxygen

Retarded Growth of Sputtered HfO2 Films on Germanium

2004 ◽  
Vol 811 ◽  
Author(s):  
Koji Kita ◽  
Masashi Sasagawa ◽  
Masahiro Toyama ◽  
Kentaro Kyuno ◽  
Akira Toriumi
Keyword(s):  
Film Growth ◽  
Early Stage ◽  
Gate Oxide ◽  
Interface Layer ◽  
Film Deposition ◽  
Si Substrate ◽  
Equivalent Thickness ◽  
Ternary Compounds ◽  
Si Substrates

ABSTRACTHfO2 films were deposited by reactive sputtering on Ge and Si substrates simultaneously, and we found not only the interface layer but the HfO2 film was thinner on Ge substrate compared with that on Si substrate. A metallic Hf layer has a crucial role for the thickness differences of both interface layer and HfO2 film, since those thickness differences were observed only when an ultrathin metallic Hf layer was predeposited before HfO2 film deposition. The role of metallic Hf is understandable by assuming a formation of volatile Hf-Ge-O ternary compounds at the early stage of film growth. These results show an advantage of HfO2/Ge over HfO2/Si systems from the viewpoint of further scaling of electrical equivalent thickness of the gate oxide films.

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