Investigation Of Deep Energy Levels In II-VI Compounds

1996 ◽  
Vol 442 ◽  
Author(s):  
A. Castaldini ◽  
A. Cavallini ◽  
P. Fernandez ◽  
B. Fraboni ◽  
J. Piqueras
Keyword(s):  
Optical Properties ◽  
Electrical Properties ◽  
Energy Levels ◽  
Deep Levels ◽  
Compensation Mechanism ◽  
Electrical And Optical Properties ◽  
Compensation Process ◽  
Transient Spectroscopy ◽  
Capacitance Transient

AbstractDeep levels in II-VI compounds have been investigated to understand their role in the compensation mechanism and their influence on the material electrical and optical properties. The electrical properties have been studied by current and capacitance transient spectroscopy, while the optical properties have been studied by cathodoluminescence. We have focused our attention on the traps involved in the compensation process, such as centre A and the deep levels located near midgap.

Electrical and Optical Properties of Defects by Complementary Spectroscopies

1995 ◽  
Vol 411 ◽  
Author(s):  
A. Castaldini ◽  
A. Cavallini ◽  
P. Fernandez ◽  
B. Fraboni ◽  
J. Piqueras ◽  
...  
Keyword(s):  
Optical Properties ◽  
Comparative Analysis ◽  
Electrical Properties ◽  
Optical Spectroscopy ◽  
Minority Carrier ◽  
Electrical And Optical Properties ◽  
Carrier Trap ◽  
Transient Spectroscopy ◽  
Capacitance Transient

ABSTRACTDeep levels in II-VI compounds were investigated by complementary junction and optical spectroscopy methods to assess the characteristics of the traps as well as the limits and the reliability of the techniques applied. The electrical properties have been investigated by current and capacitance transient spectroscopy, while the optical properties have been studied by cathodoluminescence. A critical and comparative analysis of the results obtained with the various methods allowed the determination of the parameters and the nature (majority or minority carrier trap) of most of the detected levels.

The Electrical and Optical Properties of Point and Extended Defects in Silicon Arising from Oxygen Precipitation

2007 ◽  
Vol 131-133 ◽  
pp. 225-232 ◽  
Author(s):  
R. Jones
Keyword(s):  
Optical Properties ◽  
Electrical Properties ◽  
Electrical Activity ◽  
Theoretical Work ◽  
Precipitation Process ◽  
Extended Defects ◽  
Dislocation Loops ◽  
Electrical And Optical Properties ◽  
Oxygen Precipitation ◽  
Oxygen Atoms

Oxygen precipitation in Si is a complex set of processes which has been studied over many years. Here we review theoretical work relating to the precipitation process. At temperatures around 450°C oxygen atoms become mobile and form a family of thermal double donors. The structure of these defects and the origin of their electrical activity is discussed. At temperature around 650°C these donors disappear and there is a growth of SiO2 precipitates along with rod like defects which are extended defects involving Si interstitials. At higher temperatures these collapse into dislocation loops. The structure and electrical properties of the rod like defect are described and compared with those of dislocations.

Optical and Electrical Properties of TiO2 Nanotubes Grown by Titanium Anodization

2009 ◽  
Vol 1178 ◽  
Author(s):  
Yahya Alivov ◽  
Vladimir Kuryatkov ◽  
Mahesh Pandikunta ◽  
Gautam Rajanna ◽  
Daniel Johnstone ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electrical Properties ◽  
Tio2 Nanotubes ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Electrochemical Anodization ◽  
Voltage Range ◽  
Wide Range ◽  
Transient Spectroscopy ◽  
Tio2 Nts

AbstractIn this work we investigated the structural, electrical, and optical properties of titanium dioxide (TiO2) nanotubes (NTs) formed by electrochemical anodization of Ti metal sheets in NH4F+glycerol electrolyte at different anodization voltages (Va) and acid concentrations. Our results revealed that TiO2 NTs can be grown in a wide range of anodization voltages from 10 V to 240 V. The maximum NH4F acid concentration, at which NTs can be formed, decreases with the anodization voltage, which is 0.7% for Va<60V, and decreases to 0.1% at Va =240 V. Glancing angle X-ray diffraction (GAXRD) experiments show that as-grown amorphous TiO2 transforms to anatase phase after annealing at 400 oC, and further transforms to rutile phase at annealing temperatures above 500 oC. Samples grown in 30-120 voltage range have higher crystal quality as seen from anatase (101) peak intensity and reduced linewidth. The electrical resistivity of the NTs varies with Va concentration and increases by eight orders of magnitude when Va increases from 10 V to 240 V. This is consistent with cathodoluminescense studies which showed improved optical properties for samples grown in this voltage range. Optical properties of samples were also studied by low temperature photoluminescence. Temperature dependent I-V and photo-induced current transient spectroscopy were employed to analyze electrical properties and defect structure on NT samples.

Shallow and Deep Level Defects in GaN

1995 ◽  
Vol 395 ◽  
Author(s):  
W. Götz ◽  
N.M. Johnson ◽  
D.P. Bour ◽  
C. Chen ◽  
H. Liu ◽  
...  
Keyword(s):  
Deep Level ◽  
Variable Temperature ◽  
Shallow Donor ◽  
Deep Levels ◽  
Electron Photoemission ◽  
Hall Effect Measurements ◽  
Transient Spectroscopy ◽  
P Type ◽  
Capacitance Transient ◽  
Threshold Energies

ABSTRACTShallow and deep electronic defects in MOCVD-grown GaN were characterized by variable temperature Hall effect measurements, deep level transient spectroscopy (DLTS) and photoemission capacitance transient spectroscopy (O-DLTS). Unintentionally and Si-doped, n-type and Mg-doped, p-type GaN films were studied. Si introduces a shallow donor level into the band gap of GaN at ∼Ec - 0.02 eV and was found to be the dominant donor impurity in our unintentionally doped material. Mg is the shallowest acceptor in GaN identified to date with an electronic level at ∼Ev + 0.2 eV. With DLTS deep levels were detected in n-type and p-type GaN and with O-DLTS we demonstrate several deep levels with optical threshold energies for electron photoemission in the range between 0.87 and 1.59 eV in n-type GaN.

Electrical Properties and Microstructures of Ultraviolet Transparent Ga2O3 Thin Films

2007 ◽  
Vol 561-565 ◽  
pp. 1233-1236
Author(s):  
Yasuhiro Shigetoshi ◽  
Susumu Tsukimoto ◽  
Hidehisa Takeda ◽  
Kazuhiro Ito ◽  
Masanori Murakami
Keyword(s):  
Thin Films ◽  
Electrical Resistivity ◽  
Optical Properties ◽  
Electrical Properties ◽  
Substrate Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Partial Pressure Of Oxygen ◽  
Electrical And Optical Properties ◽  
Sputtering Deposition

The electrical and optical properties, and microstructures of 100 nm-thick Ga2O3 films fabricated on Al2O3(0001) substrates by a sputtering deposition were investigated. The partial pressure of oxygen was controlled and the substrate temperature was kept to be 500 °C during deposition. With increasing the oxygen partial pressure, the structures of the Ga2O3 films deposited on the substrates were observed to change from amorphous to crystalline (monoclinic β-type Ga2O3). The transmittance of the Ga2O3 films was measured to be more than 80 % at the visible and ultraviolet regions although the electrical resistivity was high. In order to obtain both low electrical resistivity and high transmittance at the ultraviolet regions, the addition of active dopant elements such as Sn into the Ga2O3 films would be required.

Preparation and Study the Electrical and Optical Properties for (PVA-PEG-Sr2O3) Nanocomposites

2021 ◽  
Vol 19 (10) ◽  
pp. 47-55
Author(s):  
Safa Ahmed Jabbar Al-Rubaye ◽  
Nassar A. Al-lsawi ◽  
Ali R. Abdulridha
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Electrical Properties ◽  
Dielectric Loss ◽  
Energy Gap ◽  
Antimony Oxide ◽  
Optical And Electrical Properties ◽  
Electrical And Optical Properties ◽  
Constant E

In the presented work, the optical and electrical properties of composite materials (PVA-PEG-Sr2O3) were measured, as the electrical properties were verified at various frequencies in range of 100 Hz-6 MHz. In addition, the experimental results showed that the increase in frequency causes a reduction in the dielectric loss (δ) and dielectric constant (ɛ), and there is an increase in ɛ due to the increase in the content of antimony oxide (Sr2O3). It increases with increasing frequency and decreases with increasing Sr2O3 content in PVA-PEG-Sr2O3 compounds, the result of the optical properties of the nanoparticles (PVA-PEG-Sr2O3) showed that the values transmittance and energy gap were reduced with the increases in the concentrations of Sr2O3 NPs, whereas the values related to extinction coefficient, absorption coefficient, optical conductivity, refractive index, and dielectric constant (imaginary, real) were increased with increase in the concentration of Sr2O3 NPs.

Transient Capacitance Characterization of Deep Levels in Undoped and Si-Doped GaN

2003 ◽  
Vol 764 ◽  
Author(s):  
S. Nakamura ◽  
P. Liu ◽  
M. Suhara ◽  
T. Okumura
Keyword(s):  
Chemical Vapor ◽  
Deep Levels ◽  
Yellow Luminescence ◽  
Capacitance Measurements ◽  
Transient Capacitance ◽  
Si Doped ◽  
Transient Spectroscopy ◽  
Capacitance Transient ◽  
Isothermal Capacitance Transient Spectroscopy

AbstractThe deep levels in both undoped and Si-doped GaN layer grown by metalorganic chemical vapor deposition have been characterized by photocapacitance and transient capacitance spectroscopy. The increase in the photocapacitance was observed in both GaN samples in the range of 1.8 to 2.2 eV. This is due to the photoionization of carriers from the deep levels associated with the yellow luminescence (YL). In addition, the transient capacitance measurements after the photoionization were also performed in the range of 1.8 to 3.4 eV. The notable transient of capacitance was observed at the photon energies of about 2.1 and 3.4 eV, the former could be associated with the change in the charge state of the YL center and latter might stem from some other defects capturing photogenerated carriers. By using the isothermal capacitance transient spectroscopy (ICTS) analysis, the ICTS peaks due to the deep levels associated with YL were detected at about t = 150 s in both GaN samples. In addition, another ICTS peak was detected only in the Si-doped GaN samples. It is considered that this peak is associated with the deep levels deeper than YL levels and the deeper levels originate from defects induced by Si doping.

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