The Electronic Properties of a-Si:H Deposited With Hydrogen or Helium Dilution

1996 ◽  
Vol 420 ◽  
Author(s):  
F. Zhong ◽  
W. S. Hong ◽  
V. Perez-Mendez ◽  
C. C. Chen ◽  
J. D. Cohen
Keyword(s):  
Defect Density ◽  
Schottky Diodes ◽  
Growth Conditions ◽  
Drive Level ◽  
Standard Samples ◽  
Level Densities ◽  
Helium Dilution ◽  
Neutral Defect ◽  
Defect Densities ◽  
Deposition Conditions

AbstractWe have applied the Drive-Level Capacitance Profiling (DLCP) method to n-i-p a-Si:H diodes to characterize the mid-gap defect densities in the i layer. Our results show that there are no significant changes in the drive-level densities, Ndl, in n-i-p diodes and p+-i-m as well as n-i-m Schottky diodes, which indicates that DLCP can directly provide reliable energy distribution and spatial distribution of the mid-gap defects in the n-i-p device. We have found that the ratio of Ndl to ND*, the ionized defect density determined by hole onset measurement, is changed with the deposition conditions; it is 3 for standard samples, 2 for helium diluted samples and 6 for hydrogen diluted samples. These results indicate that there may be different defect distributions in these materials, which suggest the ratio of charged (D-) density to the neutral defect (D0) density may be altered when growth conditions are varied.

Effect of C Impurities in a-Si:H as Measured by Drive-Level Capacitance, Photo Current, and Electron Spin Resonance

1993 ◽  
Vol 297 ◽  
Author(s):  
J. Hautala ◽  
T. Unold ◽  
J.D. Cohen
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Defect Density ◽  
Drive Level ◽  
Level Data ◽  
Definite Effect ◽  
Wide Range ◽  
Spin Resonance ◽  
Defect Densities ◽  
Photo Current

The effect of C impurities in a-Si:H in levels of 0.4 to 2.6 at. % were studied over a wide range of metastable defect densities. Three complimentary experimental techniques [electron spin resonance (ESR), drive-level capacitance (DLC) and photo-current] were employed to track the material's defect density with light soaking and annealing, as well as Urbach energies, midgap absorption and mobility gaps energies as a function of the C content. Our results show C impurities have a definite effect on the initial and saturated defect densities, as well as the midgap absorption and Urbach energies at levels 1 at. % and above. The results indicate that C acts mainly as a center for increased disorder in the material which results in an increase in the bandtail widths, and consequently an increase in intrinsic defects. Comparison to the ESR and drive-level data show an excellent agreement between these two techniques in determining the bulk defect densities in a-Si:H.

Optimization of the Deposition Conditions for High-Gap a-Si,Ge:H,F Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
P.A. Morin ◽  
N.W. Wang ◽  
S. Wagner
Keyword(s):  
Figure Of Merit ◽  
Defect Density ◽  
Initial Defect ◽  
Optical Gap ◽  
Deposition Parameters ◽  
Defect Densities ◽  
Deposition Conditions

ABSTRACTWe report the deposition parameters for optimized a-Si,Ge:H,F alloys in the range of optical (Taue) gap 1.5 leV to 1.62eV. These deposition parameters were optimized using the saturated defect density as a figure of merit. We report initial defect densities at or below 2.5×1016 cm-3, saturated defect densities below 9×1016 cm-3, photoconductivities (at G = 1021 cm-3s-1) between 8.7×10-6 Scm-1 and 7×10-5 Scm-land photosensitivities between 104 and 105 for alloys in this range of optical gap.

Material Properties of a-SiGe:H Solar Cells as a Function of Growth Rate

2010 ◽  
Vol 1245 ◽  
Author(s):  
Peter Hugger ◽  
JinWoo Lee ◽  
J. David Cohen ◽  
Guozhen Yue ◽  
Xixiang Xu ◽  
...  
Keyword(s):  
Valence Band ◽  
Material Properties ◽  
Defect Density ◽  
Schottky Contact ◽  
Drive Level ◽  
Measurement Methods ◽  
Device Performance ◽  
Band Tail ◽  
Contact Devices ◽  
Defect Densities

AbstractWe have examined a series of a Si,Ge:H alloy devices deposited using both RF and VHF glow discharge in two configurations: SS/n+/i (a-SiGe:H)/p+/ITO nip devices and SS/n+/i (a-SiGe:H)/Pd Schottky contact devices, over a range of deposition rates. We employed drive-level capacitance profiling (DLCP), modulated photocurrent (MPC), and transient junction photo-current (TPI) measurement methods to characterize the electronic properties in these materials. The DLCP profiles indicated quite low defect densities (mid 1015 cm-3. to low 1016 cm-3 depending on the Ge alloy fraction) for the low rate RF (∼1Å/s) deposited a-SiGe:H materials. In contrast to the RF process, the VHF deposited a-SiGe:H materials did not exhibit nearly as rapid an increase of defect density with the deposition rate, remaining well below 1017 cm-3. up to rates as high as 10Å/s. Simple examination of the TPI spectra on theses devices allowed us to determine valence band-tail widths.. Modulated photocurrent (MPC) obtained for several of these a-SiGe:H devices allowed us to deduce the conduction band-tail widths. In general, the a-Si,Ge:H materials exhibiting narrower valence band-tail widths and lower defect densities correlated with the best device performance.

On Applicability of Time-Resolved Optical Techniques for Characterization of Differently Grown 3C-SiC Crystals and Heterostructures

2012 ◽  
Vol 711 ◽  
pp. 159-163 ◽  
Author(s):  
Patrik Ščajev ◽  
Pavels Onufrijevs ◽  
Georgios Manolis ◽  
Mindaugas Karaliūnas ◽  
Saulius Nargelas ◽  
...  
Keyword(s):  
Room Temperature ◽  
Defect Density ◽  
Growth Conditions ◽  
Free Carrier ◽  
Band Edge Emission ◽  
Free Carrier Absorption ◽  
Free Standing ◽  
Optical Techniques ◽  
Time Resolved ◽  
Photoelectrical Properties

We applied a number of time-resolved optical techniques for investigation of optical and photoelectrical properties of cubic SiC grown by different technologies on different substrates. The excess carriers were injected by a short laser pulse and their dynamics was monitored by free-carrier absorption, light-induced transient grating, and photoluminescence techniques in a wide excitation range. Combining an optical and electrical probe beam delay, we found that free carrier lifetimes in differently grown layers vary from few ns up to 20 μs. Temperature dependences of carrier diffusivity and lifetime revealed a pronounced carrier trapping in thin sublimation grown layers. In free-standing layers and thick sublimation layers, the ambipolar mobility was found the highest (120 cm2/Vs at room temperature). A linear correlation between the room-temperature band edge emission and carrier lifetime in differently grown layers was attributed to defect density, strongly dependent on the used growth conditions.

Growth and Characterization of 2″ 6H-Silicon Carbide

1999 ◽  
Vol 572 ◽  
Author(s):  
Erwin Schmitt ◽  
Robert Eckstein ◽  
Martin Kölbl ◽  
Amd-Dietrich Weber
Keyword(s):  
Silicon Carbide ◽  
Boundary Conditions ◽  
Growth Process ◽  
Defect Density ◽  
Crystal Quality ◽  
Process Conditions ◽  
Thermal Boundary Conditions ◽  
Sublimation Growth ◽  
Defect Densities

ABSTRACTFor the growth of 2″ 6H-SiC a sublimation growth process was developed. By different means of characterization crystal quality was evaluated. Higher defect densities, mainly in the periphery of the crystals were found to be correlated to unfavourable process conditions. Improvement of thermal boundary conditions lead to a decreased defect density and better homogeneity over the wafer area.

Investigation of the Defect Size and Density in Thin SiON Filmfor Organic Device Encapsulation

2016 ◽  
Vol 2016 (1) ◽  
pp. 000272-000276
Author(s):  
Kunmo Chu ◽  
Ki Deok Bae ◽  
Byong Gwon Song ◽  
Yong Young Park ◽  
Jaekwan Kim ◽  
...  
Keyword(s):  
Defect Density ◽  
Chemical Vapor ◽  
Defect Size ◽  
Intrinsic Defect ◽  
Ni Substrate ◽  
Defect Site ◽  
Defect Sites ◽  
Chemical Vapor Deposited ◽  
Density Values ◽  
Defect Densities

Abstract In this study, thin SiON was grown by plasma enhanced chemical vapor deposited (PECVD) method as a thin-film encapsulation (TFE) layer. For defect visualization, electroplating results in a Cu bump grown at each defect site in the SiON film where electrolytic solution establishes contact with the Ni substrate. It was inferred that the Cu bump density could be representative of the intrinsic defect densities for the SiON film. The defect density values were obtained by monitoring the Cu bumps grown at defect sites in the SiON films and then evaluating the number of densities of the Cu bumps for the corresponding defect densities.At the same time, by analyzing the cross section of the Cu bumps grown on SiON film, a linear relation between the Cu bump diameter and the defect size increase was obtained. We expect that this electroplating method allows for rapid visualization of defect distribution and quality evaluation of TFE layers.

The Effects of Hydrogen Profiling and of Light-Induced Degradation on the Electronic Properties of Hydrogenated Nanocrystalline Silicon

2005 ◽  
Vol 862 ◽  
Author(s):  
A.F. Halverson ◽  
J.J. Gutierrez ◽  
J.D. Cohen ◽  
Baojie Yan ◽  
Jeffrey Yang ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Minority Carrier ◽  
Defect Density ◽  
Light Exposure ◽  
Nanocrystalline Silicon ◽  
Drive Level ◽  
Dramatic Decrease ◽  
Transient Photocurrent ◽  
Hydrogen Dilution ◽  
Carrier Collection

AbstractThe electronic properties of hydrogenated nanocrystalline silicon (nc-Si:H) were studied using junction capacitance methods. Drive-level capacitance profiling (DLCP) measurements revealed significant differences for nc-Si:H layers deposited under constant hydrogen dilution compared to those deposited using hydrogen profiling, with lower DLCP densities in the latter case. Transient photocapacitance (TPC) measurements revealed the mixed-phase nature of these materials. It disclosed spectra that appeared quite microcrystalline-like at lower temperatures, but more similar to a-Si:H at higher temperatures where the minority carrier collection is higher in the nanocrystalline component of these samples. This then suppresses the TPC signal from this component compared to the a-Si:H component. In contrast, because transient photocurrent signals are enhanced by the additional minority carrier collection, those spectra appear microcrystalline like at all temperatures. We also investigated the effects of light-induced degradation in these devices. This caused a dramatic decrease in hole collection, similar to that caused by reducing the measurement temperature of the samples. However, the light exposure did not appear to increase the deep defect density (dangling bonds).

Defect density in a metal-monolayer-metal cell

1980 ◽  
Vol 33 (8) ◽  
pp. 1713 ◽  
Author(s):  
IR Peterson
Keyword(s):  
Defect Density ◽  
High Surface ◽  
Langmuir Blodgett ◽  
Minimum Deformation ◽  
Defect Densities

Techniques for Langmuir-Blodgett monolayer deposition at high surface pressures and with minimum deformation have been studied by measurement of the resultant defect densities in a metal-monolayer-metal cell.

MOCVD Growth and Characterization of High-Quality ZnSe on GaAs

1994 ◽  
Vol 340 ◽  
Author(s):  
J. C. Chen ◽  
Bing Yang ◽  
F. Semendy ◽  
W. W. Clark ◽  
P. R. Boyd ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Secondary Ion Mass Spectrometry ◽  
Defect Density ◽  
Growth Conditions ◽  
Misfit Dislocations ◽  
High Quality ◽  
Double Crystal ◽  
X Ray ◽  
Mocvd Growth ◽  
Order Of Magnitude

ABSTRACTHigh-quality ZnSe epilayers on GaAs substrates have been grown by MOCVD. Diethylzinc (DEZn) and diethylselenide (DESe) were used as source materials. Growth studies were done at 400°C under different growth conditions in an atmospheric pressure MOCVD reactor. The as-grown ZnSe epilayers were characterized by a wide variety of techniques, such as double crystal x-ray diffraction, low-temperature photoluminescence (PL), transmission electron microscopy (TEM), secondary ion mass spectrometry (SIMS), and scanning electron microscopy (SEM).The results show excellent structural and optical properties of ZnSe. The best material was grown on undoped GaAs at the VI/II ratio near unity. The full-width-at-half-maximum (FWHM) of ZnSe (∼0.2/μm thick) x-ray peak as low as 90 arc seconds was achieved. TEM results also show very low defect density. The density of stacking faults is less than 105/cm2 which is four orders of magnitude less than that of samples grown by conventional MBE [J. Petruzzello et al. J. Appl. Phys. 63, 2299 (1988)] and MOCVD [J.L. Batstone et al. Philos. Mag A, 66, 609, 1992]. The spacing between misfit dislocations is between 5 to 10,μm which is one order of magnitude larger than that of reported sample of comparable thickness.

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