Electrical Properties of the Multilayer Structures Based on Ultrathin Diamond-Like Carbon Films

1996 ◽  
Vol 452 ◽  
Author(s):  
V. I. Polyakov ◽  
P. I. Perov ◽  
N. M. Rossukanyi ◽  
A. I. Rukovishnikov ◽  
A. V. Khomich ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Band Gap ◽  
Cross Sections ◽  
Deep Level ◽  
Energy Levels ◽  
Differential Resistance ◽  
Carbon Films ◽  
Multilayer Structures ◽  
Transient Spectra ◽  
Trapping Centers

AbstractThe electrical characteristics of multilayer structures based on amorphous ultrathin diamondlike carbon films were investigated including dynamic and quasi-static current-voltage characteristics, capacitance-voltage characteristics, deep level transient spectra. The effect of illumination and temperature on these characteristics was also investigated. For the multilayer structures composed of lower band gap amorphous carbon layers separated with higher band gap ones, there were observed well-defined regions of negative differential resistance and sharp 20-fold changes in capacitance at definite voltages. Activation energies, capture cross sections, and locations of trapping centers were defined. The effects observed are discussed in terms of trap-assisted tunneling and, also, in terms of resonant tunneling between energy levels in superlattices and charge filling of the quantum wells and trapping centers.

Deep Levels in Superlattices

1989 ◽  
Vol 163 ◽  
Author(s):  
John D. Dow ◽  
Shang Yuan Ren ◽  
Jun Shen ◽  
Min-Hsiung Tsai
Keyword(s):  
Band Gap ◽  
Quantum Confinement ◽  
Deep Level ◽  
Energy Levels ◽  
Deep Trap ◽  
Shallow Donor ◽  
Deep Levels ◽  
Band Gap Engineering ◽  
Substitutional Impurities ◽  
Superlattice Period

AbstractThe physics of deep levels in semiconductors is reviewed, with emphasis on the fact that all substitutional impurities produce deep levels - some of which may not lie within the fundamental band gap. The character of a dopant changes when one of the deep levels moves into or out of the fundamental gap in response to a perturbation such as pressure or change of host composition. For example, Si on a Ga site in GaAs is a shallow donor, but becomes a deep trap for x>0.3 in AℓxGa1-xAs. Such shallow-deep transitions can be induced in superlattices by changing the period-widths and quantum confinement. A good rule of thumb for deep levels in superlattices is that the energy levels with respect to vacuum are relatively insensitive (on a >0.1 eV scale) to superlattice period-widths, but that the band edges of the superlattices are sensitive to changes of period. Hence the deep level positions relative to the band edges are sensitive to the period-widths, and shallow-deep transitions can be induced by band-gap engineering the superlattice periods.

Multi-Exponential Analysis of DLTS by Contin

1986 ◽  
Vol 69 ◽  
Author(s):  
Jun Morimoto ◽  
Tatsuo Kida ◽  
Toru Miyakawa
Keyword(s):  
Continuous Spectrum ◽  
Cross Sections ◽  
Emission Rate ◽  
Deep Level ◽  
Energy Levels ◽  
Three Dimensional ◽  
Deep Impurity ◽  
Junction Capacitance ◽  
Single Temperature ◽  
Single Exponential

AbstractDeep level transient spectroscopy (DLTS), which assumes a single exponential decay form for the transient junction capacitance, is the most commonly used method to characterize deep impurity levels in semiconductors. However conventional DLTS may lead to erroneous results if there are several closely spaced energy levels or the emission rate has a continuous spectrum. To overcome this difficulty a novel method named the multi-exponential analysis of DLTS by CONTIN (MEDLTS by CONTIN) is proposed. This method analyzes the emission rate to have a finite continuous spectrum S(λ) which appears in the transient junction capacitance C(t)=, by using the program “CONTIN” developed by Provencher in biophysics. Even if S(λ) includes two peaks at λ1 and λ2, those peaks can be distinguished for λ2/ λ1>2. As an example of the application of this method, deep levels in Si:Au were experimentally investigated. According to the three dimensional S(λ)-T2/λ-1/T representation, the single peak in the conventional DLTS was clarified to consist of two adjacent levels with activation energies and capture cross sections EB1=0.51eV, σB1=4.0×10−15cm2 and EB2=0.47eV, σB2=1.1×10−15cm2. With the assumption of the finite continuous spectrum S(λ) for the emission rate, MEDLTS by CONTIN permits one to get much information correctly. MEDLTS by CONTIN is superior to the conventional DLTS because it is a single-temperature scan, multi-exponential analysis instead of the conventional multi-temperature scan, single-exponential analysis.

Probing Metal Defects in CCD Image Sensors

1995 ◽  
Vol 378 ◽  
Author(s):  
William C. McColgin ◽  
J. P. Lavine ◽  
C. V. Stancampiano
Keyword(s):  
Cross Sections ◽  
Dark Current ◽  
Deep Level ◽  
Energy Levels ◽  
Image Sensors ◽  
Current Generation ◽  
Charge Coupled Device ◽  
Iron Nickel ◽  
Relationship Of ◽  
Ccd Image

AbstractWe have investigated the role of heavy metals in causing visible pixel defects in Charge Coupled Device (CCD) image sensors. Using a technique we call dark current spectroscopy, we can probe for deep-level traps in the active areas of completed image sensors with a sensitivity of 1 × 109 traps/cm3 or better. Analysis of histograms of dark current images from these sensors shows that the presence of traps causes quantization in the dark current. Different metal traps have characteristic dark current generation rates that can identify the contaminant trap. By examining the temperature dependence of the dark current generation, we have calculated the energy levels and generation cross sections for gold, iron, nickel, and cobalt. Our results show the relationship of these traps to the “white spot” defects reported for image sensors.

Deep Level Defects, Luminescence, and the Electro-Optic Properties of SiGe/Si Heterostructures

1993 ◽  
Vol 325 ◽  
Author(s):  
Pallab Bhattaci-Iarya ◽  
Shin-Hwa Li ◽  
Jinju Lee ◽  
Steve Smith
Keyword(s):  
Quantum Wells ◽  
Cross Sections ◽  
Quantum Wires ◽  
Deep Level ◽  
Luminescent Properties ◽  
Deep Levels ◽  
Electro Optic ◽  
B Doping ◽  
P Type ◽  
Capture Cross Sections

AbstractDeep levels and luminescence in SiGe/Si heterostructures and quantum wells have been investigated. We have studied the effects of Be- and B-doping on the luminescent properties of Si1−xGex/Si single and multiquantum wells. No new levels, or enhancement of luminescence, from that in undoped samples, is detected in samples which are selectively doped in the well-regions, implying that the observed luminescence in the undoped quantum wells is a result of alloy disordering. Slight enhancement of luminescence is observed in disordered wells and in quantum wires made by electron beam lithography and dry etching. Deep levels have been identified and characterized in undoped Si1-xGex alloys. Hole traps in the p-type layers have activation energies ranging from 0.029-0.45 eV and capture cross sections (σ∞) ranging from 10−9 to 10−20 cm2. Possible origins of these centers are discussed. Some possibilities of obtaining enhanced electro-optic coefficients in SiGe/Si heterostructures are discussed.

EuTe/PbTe Superlattices: Mbe Growth and Optical Characterization

1993 ◽  
Vol 301 ◽  
Author(s):  
G. Springholz ◽  
Shu Yuan ◽  
G. Bauer ◽  
M. Kriechbaum ◽  
H. Krenn
Keyword(s):  
Quantum Wells ◽  
Band Gap ◽  
Growth Parameters ◽  
Energy Levels ◽  
Wide Band ◽  
Growth Conditions ◽  
High Energy ◽  
Layer By Layer ◽  
Heteroepitaxial Growth ◽  
Mbe Growth

ABSTRACTThe heteroepitaxial growth of EuTe on PbTe (111) by molecular beam epitaxy (MBE) was investigated using in situ reflection high energy electron diffraction (RHEED). As a function of substrate temperature and Te2 flux rate, the resulting EuTe (111) surfaces exhibit several different surface reconstructions corresponding to Te-stabilized or Eu-stabilized surfaces. The Eustabilized surface shows a (2√3 × 2√3)R30° surface reconstruction. Because of the strain induced tendency for 3D islanding, only in a narrow window of MBE growth parameters perfect 2D layer-by-layer heteroepitaxial growth exists. Using such optimized MBE growth conditions, we have fabricated a series of PbTe/EuTe superlattices. In such superlattices the wide band gap EuTe layers act as barriers and the narrow band gap PbTe as quantum wells. The superlattices were investigated by high resolution x-ray diffraction, showing their high structural perfection. Modulated low temperature Fourier transform infrared reflection measurements were performed in order to determine the confined energy levels in the PbTe quantum wells. The measurements indicate that mini-subbands are formed in the PbTe quantum wells with a mini-band width of 22 meV in agreement with envelope function calculations.

Deep Level Defect Characterization of MBE Grown Ingaas/Gaas Heterostructures.

1990 ◽  
Vol 209 ◽  
Author(s):  
W.R. Buchwald ◽  
J.H. Zhao ◽  
F.C. Rong
Keyword(s):  
Conduction Band ◽  
Cross Sections ◽  
Deep Level ◽  
Schottky Diodes ◽  
Energy Levels ◽  
Depth Profiling ◽  
Defect Characterization ◽  
Deep Level Defect ◽  
Transient Spectroscopy

ABSTRACTDeep level transient spectroscopy (DLTS) measurements have been performed on Schottky diodes fabricated on MBE grown InGaAs/GaAs heterostructures. The dominant electron trap in this material is found at a depth of 0.30eV below the GaAs conduction band and is believed to be the previously observed M3 defect. Two other defects, at depths of 0.50eV and 0.58eV below the GaAs conduction band, were also observed. Defect depth profiling shows the 0.50eV defect to be spatially locatednear the heterointerface. The 0.58eV defect is not observed near the heterointerface but is observed in large concentrations deep in the GaAs epilayer. Optical DLTS measurements reveal deep defects at 0.54eV and 0.31eV above the InGaAs valence band as well as a large, broad peak, most likely consisting of several energy levels with varying capture cross sections,located at the heterointerface. Two carrier accumulation peaks were also seen in the CV carrier profiling measurements and are suggested to be due to two heterointerface defects located at 0.68eV and 0.87eV below the GaAs conduction band.Thermally stimulated capacitance measurements also indicate minority hole emission in this n-InGaAs/N-GaAs heterostructure.

scholarly journals Deep levels in semiconductors

1985 ◽  
Vol 63 (7) ◽  
pp. 1666-1671 ◽  
Author(s):  
B. A. Lombos
Keyword(s):  
Transport Properties ◽  
Tin Oxide ◽  
Multilevel Model ◽  
Energy Gap ◽  
Deep Level ◽  
Energy Levels ◽  
Transparent Electrode ◽  
Dangling Bonds ◽  
Trapping Centers

The role of deep-lying trapping centers in semi-insulating GaAs, polysilicon and polycrystalline tin oxide transparent electrode has been systematically investigated. It was demonstrated that some of the peculiar transport properties of these semiconductors can be elucidated by deep level compensation. A multilevel model is presented to determine the position of the Fermi level as a function of impurity concentrations. These include, quantitatively, the deep-lying levels which have been introduced by doping in the case of GaAs and by grain boundaries in the case of polycrystalline films. In the latter cases the dangling bonds, associated to lattice defects, are characterized by energy levels which are localized in the energy gap. These dangling bonds can act as electron traps when empty and hole traps when occupied. These are the deep levels.In each of the investigated three cases, this concept permitted the elucidation of some of the transport properties of these semiconductors.

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