scholarly journals Comparison of VHF, RF and Dc Plasma Excitation for a-Si:H Deposition with Hydrogen Dilution

1998 ◽  
Vol 507 ◽  
Author(s):  
R. Platz ◽  
C. Hof ◽  
S. Wieder ◽  
B. Rech ◽  
D. Fischer ◽  
...  
Keyword(s):  
Growth Rate ◽  
Substrate Temperature ◽  
Transport Properties ◽  
Electronic Transport ◽  
Chemical Vapor ◽  
Dilution Ratio ◽  
Electronic Transport Properties ◽  
Optical Gap ◽  
Hydrogen Dilution ◽  
The Stability

ABSTRACTA comparative study of DC, RF and VHF excitation for the plasma enhanced chemical vapor deposition (PECVD) of intrinsic layers of a-Si:H is presented, with special emphasis on the effects of hydrogen dilution. Growth rates at comparable plasma power, for substrate temperatures between 100°C and 300°C and for various H2 dilution ratios are presented, along with optical bandgap, H content, and electronic transport properties in the light-soaked state.H2 strongly reduces the growth rate for all techniques. The growth rate for the highest H2 dilution ratio is approximately four times higher for VHF than for DC or RF excitation. In all three cases increasing the substrate temperature reduces the optical gap and the H content CH. Raising the substrate temperature slightly enhances the stability of undiluted films. H2 dilution increases the optical gap for all three techniques. The H content of RF- and VHF-deposited samples increases with increasing H2 dilution ratio, while in DC deposition it produces an initial drop of the H content, followed by an increase.In all three cases, H2 dilution improves the electronic transport properties of the material by roughly a factor of two. The gain in stability is most pronounced for relatively small dilution; in the case of DC deposition, too strong a dilution even has an adverse effect on stability.

Influence of Substrate Temperature and Hydrogen Dilution Ratio on the Properties of Nanocrystalline Silicon Thin Films Grown by Hot-Wire Chemical Vapor Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
H.R. Moutinho ◽  
C.-S. Jiang ◽  
B. Nelson ◽  
Y. Xu ◽  
J. Perkins ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Seed Layer ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Dilution Ratio ◽  
Crystal Silicon ◽  
Silicon Thin Films ◽  
Hydrogen Dilution ◽  
Influence Of Substrate

AbstractWe have studied the influence of substrate temperature and hydrogen dilution ratio on the properties of silicon thin films deposited on single-crystal silicon and glass substrates. We varied the initial substrate temperature from 200° to 400°C and the dilution ratio from 10 to 100. We also studied the effectiveness of the use of a seed layer to increase the crystallinity of the films. The films were analyzed by atomic force microscopy, X-ray diffraction, Raman spectroscopy, and transmission and scanning electron microscopy. We found that as the dilution ratio is increased, the films go from amorphous, to a mixture of amorphous and crystalline, to nanocrystalline. The effect of substrate temperature is to increase the amount of crystallinity in the film for a given dilution ratio. We found that the use of a seed layer has limited effects and is important only for low values of dilution ratio and substrate temperature, when the films have large amounts of the amorphous phase.

The Effect of Hydrogen Dilution on the Deposition of Sige Alloys and the Device Stability

1991 ◽  
Vol 219 ◽  
Author(s):  
L. Yang ◽  
L. Chen ◽  
A. Catalano
Keyword(s):  
Ir Spectroscopy ◽  
Glow Discharge ◽  
Transport Properties ◽  
Diffusion Length ◽  
Light Exposure ◽  
Dc Glow Discharge ◽  
Dilution Ratio ◽  
Hydrogen Dilution ◽  
Device Stability ◽  
The Stability

ABSTRACTWe have studied the structural and transport properties of a-Si1−x Gex:H alloys made by DC glow discharge of SiH4 and GeH4 with substantial amount of H2 dilution. The dilution ratio, i.e. H2/(SiH4 + GeH4), was varied up to 40:1. IR spectroscopy revealed that H2 dilution greatly suppresses the tendency of forming microvoids due to Ge incorporation. Photoconductivity and ambipolar diffusion length, which represent transport properties of electrons and holes respectively, are also significantly improved by using H2 dilution. At a dilution ratio of 20:1, the electron υτ product reached 10-6 cm2/V at a bandgap 1.55 eV which is even larger than that of a device quality a-Si:H. Solar cells using alloy i-layers made with H2 dilution were fabricated. The stability of the devices under light exposure was found to be much improved with increasing H2 dilution, suggesting a strong correlation between the stability and the density of microvoids.

Characterization of Microcrystalline Transition from Amorphous Silicon as a Function of Hydrogen Dilution and Substrate Temperature of Hot-wire CVD

2002 ◽  
Vol 715 ◽  
Author(s):  
Keda Wang ◽  
Haoyue Zhang ◽  
Jian Zhang ◽  
Jessica M. Owens ◽  
Jennifer Weinberg-Wolf ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Sudden Change ◽  
Chemical Vapor ◽  
Threshold Value ◽  
Ir Absorption ◽  
Sudden Increase ◽  
Hot Wire ◽  
Hydrogen Dilution ◽  
Integral Absorption ◽  
Two Peaks

Abstracta-Si:H films were prepared by hot wire chemical vapor deposition. One group was deposited at a substrate temperature of Ts=250°C with varied hydrogen-dilution ratio, 0<R<10; the other group was deposited with fixed R=3 but a varied Ts from 150 to 550°C. IR, Raman and PL spectra were studied. The Raman results indicate that there is a threshold value for the microstructure transition from a- to μc-Si. The threshold is found to be R ≈ 2 at Ts = 250°C and Ts ≈ 200°C at R=3. The IR absorption of Si-H at 640 cm-1 was used to calculate the hydrogen content, CH. CH decreased monotonically when either R or Ts increased. The Si-H stretching mode contains two peaks at 2000 and 2090 cm-1. The ratio of the integral absorption peaks I2090/(I2090+I2090) showed a sudden increase at the threshold of microcrystallinity. At the same threshold, the PL features also indicate a sudden change from a- to μc-Si., i.e. the low energy PL band becomes dominant and the PL total intensity decreases. We attribute the above IR and PL changes to the contribution of microcrystallinity, especially the c-Si gain-boundaries.

ELECTRONIC TRANSPORT PROPERTIES OF SILICON NANOWIRE CAGE

2018 ◽  
Author(s):  
Shenqiu Mo ◽  
Dengke Ma ◽  
Lina Yang ◽  
Meng An ◽  
Zhiyu Liu ◽  
...  
Keyword(s):  
Transport Properties ◽  
Electronic Transport ◽  
Silicon Nanowire ◽  
Electronic Transport Properties

Improved thermoelectric transport properties of Ge4Se3Te through dimensionality reduction

2021 ◽  
Author(s):  
H. H. Huang ◽  
Xiaofeng Fan ◽  
Wei Tao Zheng ◽  
David J. Singh
Keyword(s):  
Dimensionality Reduction ◽  
Transport Properties ◽  
Electronic Transport ◽  
Thermoelectric Transport ◽  
Electronic Transport Properties ◽  
Thermoelectric Transport Properties

Layered semiconducting Ge4Se3Te shows unusual bonding that suggests the possibility of unusual transport that may be favorable for thermoelectrics. We investigated the electronic transport properties in relation to thermoelectricity of...

scholarly journals Effect of vacancy defects on the electronic transport properties of an Ag–ZnO–Pt sandwich structure

2021 ◽  
Vol 20 (2) ◽  
pp. 798-804
Author(s):  
G. R. Berdiyorov ◽  
F. Boltayev ◽  
G. Eshonqulov ◽  
H. Hamoudi
Keyword(s):  
Transport Properties ◽  
Electronic Transport ◽  
Density Functional ◽  
Practical Importance ◽  
Functional Formalism ◽  
Vacancy Defects ◽  
Electronic Transport Properties ◽  
Charge Localization ◽  
Metal Insulator Metal ◽  
Current Rectification

AbstractThe effect of zinc and oxygen vacancy defects on the electronic transport properties of Ag(100)–ZnO(100)–Pt(100) sandwich structures is studied using density functional theory in combination with the nonequilibrium Green’s functional formalism. Defect-free systems show clear current rectification due to voltage dependent charge localization in the system as revealed in our transmission eigenstates analysis. Regardless of the location, oxygen vacancies result in enhanced current in the system, whereas Zn vacancy defects reduce the charge transport across the junction. The current rectification becomes less pronounced in the presence of both types of vacancy defects. Our findings can be of practical importance for developing metal-insulator-metal diodes.

Sign in / Sign up

Export Citation Format

Share Document