scholarly journals A Simple Method to Differentiate between Free-Carrier Recombination and Trapping Centers in the Bandgap of the p-Type Semiconductor

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Megersa Wodajo Shura
Keyword(s):  
Energy Levels ◽  
Localized States ◽  
Recombination Rates ◽  
Simple Method ◽  
Free Carriers ◽  
Excess Carrier ◽  
Carrier Lifetimes ◽  
Localized State ◽  
Type Semiconductor ◽  
P Type

In this research, the ranges of the localized states in which the recombination and the trapping rates of free carriers dominate the entire transition rates of free carriers in the bandgap of the p-type semiconductor are described. Applying the Shockley–Read–Hall model to a p-type material under a low injection level, the expressions for the recombination rates, the trapping rates, and the excess carrier lifetimes (recombination and trapping) were described as functions of the localized state energies. Next, the very important quantities called the excess carriers’ trapping ratios were described as functions of the localized state energies. Variations of the magnitudes of the excess carriers’ trapping ratios with the localized state energies enable us to categorize the localized states in the bandgap as the recombination, the trapping, the acceptor, and the donor levels. Effects of the majority and the minority carriers’ trapping on the excess carrier lifetimes are also evaluated at different localized energy levels. The obtained results reveal that only excess minority trapping affects the excess carrier lifetimes, and excess majority carrier trapping has no effect.

Excess Carrier Lifetimes in a Bulk p-Type SiC Wafer Measured by the Microwave Photoconductivity Decay Method

2007 ◽  
Vol 556-557 ◽  
pp. 359-362 ◽  
Author(s):  
Masahiko Kawai ◽  
Tatsuhiro Mori ◽  
Masashi Kato ◽  
Masaya Ichimura ◽  
Shingo Sumie ◽  
...  
Keyword(s):  
Time Constant ◽  
Minority Carrier ◽  
Slow Component ◽  
Structural Defects ◽  
Excess Carrier ◽  
Carrier Lifetimes ◽  
Photoconductivity Decay ◽  
Increasing Temperature ◽  
P Type ◽  
Sic Wafer

We carried out mapping of the excess carrier lifetime for a bulk p-type 4H-SiC wafer by the microwave photoconductivity decay (μ-PCD) method, and we compared the lifetime map with structural defect distribution. Several small regions with short lifetimes compared with surrounding parts are found, and they correspond to regions with high-density structural defects. Excess carrier decay curves for this wafer show a slow component, which originates from minority carrier traps. From temperature dependence of the excess carrier decay curve, we found decrease of the time constant of the slow component with increasing temperature. We compared the activation energy of the time constant with that obtained from the numerical simulation, and concluded that the energy level for the minority carrier trap would be 125 meV from the conduction band.

Comparative Photocatalytic Properties of Cu2O from Octahedron to Sphere Structures

2014 ◽  
Vol 609-610 ◽  
pp. 45-50 ◽  
Author(s):  
Li Min Qian ◽  
Jie Zhou ◽  
Chu Zheng ◽  
Di Chen ◽  
Bi Shen ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Surface Characteristics ◽  
Morphology Evolution ◽  
Simple Method ◽  
Visible Light Photocatalyst ◽  
Absorption Intensity ◽  
Potential Applications ◽  
Type Semiconductor ◽  
P Type ◽  
Controllable Preparation

Cu2O, a p-type semiconductor, has broad potential applications, especially as a visible-light photocatalyst. This paper presents a simple water-bath reflux to prepare Cu2O micro/nanoparticles. The morphology evolution from intact octahedrons to surface-pitted spheres was obtained by adjusting reducing agent and additive. Reflectance spectra show similar photo-absorption intensity and the same range from 250 nm to 650 nm. However, they perform different photocatalytic activity. Intact octahedron has the best photodegradation ability and next is vertex-and edge-damaged octahedron, the lowest for vertex-free polyhedrons and surface-pitted spheres. The enhanced photocatalytic activity for intact octahedrons should to be attributed to its surface characteristics of high index. Our study not only provides a simple method for controllable preparation of Cu2O micro/nanoparticles with different morphologies but also confirms the effect of morphologies on photocatalytic activity.

Excess Carrier Lifetimes in a Bulk p-Type SiC Wafer Measured by the Microwave Photoconductivity Decay Method

2007 ◽  
pp. 359-362
Author(s):  
Masahiko Kawai ◽  
Tatsuhiro Mori ◽  
Masashi Kato ◽  
Masaya Ichimura ◽  
Shingo Sumie ◽  
...  
Keyword(s):  
Excess Carrier ◽  
Carrier Lifetimes ◽  
Photoconductivity Decay ◽  
P Type ◽  
Sic Wafer

Preparation of ZnO:Mo Thin Films by RF Sputtering

2013 ◽  
Vol 1494 ◽  
pp. 99-104 ◽  
Author(s):  
Tien-Chai Lin ◽  
Shang-Chou Chang ◽  
Wen-Chang Huang ◽  
Wen-Feng Huang
Keyword(s):  
Crystal Structure ◽  
Valence Electron ◽  
Rf Sputtering ◽  
Zno Films ◽  
Ion Scattering ◽  
Free Carriers ◽  
Scattering Effects ◽  
Type Semiconductor ◽  
Doped Zno ◽  
P Type

ABSTRACTBased on the electron configurations of Mo and Zn, the valence electron difference between Mo6+ and Zn2+ is 4. Therefore, a small amount of Mo doping can produce sufficient free carriers to reduce the ion scattering effects. The Mo doped ZnO (MZO) thin film prepared by RF sputtering was studied in this research. Structural, electrical, and optical characteristics of the films were discussed. The MZO film shows a resistivity of 1.1 × 10-2 Ω⋅cm, a carrier concentration of 2.2 × 1021 cm-3,a mobility of 0.63 cm2/V⋅s, and average transparency of 81.0% at both the powers of 20 W to the Mo target and of 125 W to the ZnO target. The MZO film becomes a stable p-type semiconductor at high power process toward Mo target. The film preserves its p-type characteristics after exposure to air for one and a half months. The crystal structure of the p-ZnO films is amorphous with an average transparency of 34.5%.

o-Carborane functionalized pentacenes: synthesis, molecular packing and ambipolar organic thin-film transistors

2015 ◽  
Vol 51 (60) ◽  
pp. 12004-12007 ◽  
Author(s):  
Jixi Guo ◽  
Danqing Liu ◽  
Jiahui Zhang ◽  
Jiji Zhang ◽  
Qian Miao ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Energy Levels ◽  
Molecular Packing ◽  
Organic Thin Film Transistors ◽  
Organic Thin Film ◽  
Homo Energy ◽  
Type Semiconductor ◽  
Pentacene Derivatives ◽  
P Type

Replacement of triisopropylsilyl groups with o-carboranyl units in pentacene derivatives can lower both LUMO and HOMO energy levels, converting a typical p-type semiconductor into an ambipolar one.

Characterization of the Excess Carrier Lifetime of As-Grown and Electron Irradiated Epitaxial p-Type 4H-SiC Layers by the Microwave Photoconductivity Decay Method

2010 ◽  
Vol 645-648 ◽  
pp. 207-210 ◽  
Author(s):  
Yoshinori Matsushita ◽  
Masashi Kato ◽  
Masaya Ichimura ◽  
Tomoaki Hatayama ◽  
Takeshi Ohshima
Keyword(s):  
Cross Sections ◽  
Carrier Lifetime ◽  
Excitation Density ◽  
Excess Carrier ◽  
Carrier Lifetimes ◽  
Photoconductivity Decay ◽  
Recombination Centers ◽  
P Type ◽  
Capture Cross Sections

We measured the excess carrier lifetimes in as-grown and electron irradiated p-type 4H-SiC epitaxial layers with the microwave photoconductivity decay (-PCD) method. The carrier lifetime becomes longer with excitation density for the as-grown epilayer. This dependence suggests that e ≥h for the dominant recombination center, where e andh are capture cross sections for electrons and holes, respectively. In contrast, the carrier lifetime does not depend on the excitation density for the sample irradiated with electrons at an energy of 160 keV and a dose of 1×1017 cm-2. This may be due to the fact that recombination centers with e <<h were introduced by the electron irradiation or due to the fact that the acceptor concentration was decreased significantly by the irradiation.

Measurement of radiative and auger recombination rates in p-type InGaAsP diode lasers

1982 ◽  
Vol 18 (14) ◽  
pp. 595 ◽  
Author(s):  
C.B. Su ◽  
J. Schlafer ◽  
J. Manning ◽  
R. Olshansky
Keyword(s):  
Auger Recombination ◽  
Diode Lasers ◽  
Recombination Rates ◽  
P Type

scholarly journals Optimization of Sb2S3 Nanocrystal Concentrations in P3HT: PCBM Layers to Improve the Performance of Polymer Solar Cells

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2152
Author(s):  
E. M. Mkawi ◽  
Y. Al-Hadeethi ◽  
R. S. Bazuhair ◽  
A. S. Yousef ◽  
E. Shalaan ◽  
...  
Keyword(s):  
Solar Cells ◽  
Doping Concentration ◽  
Polymer Solar Cells ◽  
Energy Levels ◽  
Acid Methyl Ester ◽  
Visible Absorption ◽  
Block Polymer ◽  
Coating Method ◽  
Electronic Parameters ◽  
P Type

In this study, polymer solar cells were synthesized by adding Sb2S3 nanocrystals (NCs) to thin blended films with polymer poly(3-hexylthiophene)(P3HT) and [6,6]-phenyl-C61-butyric-acid-methyl-ester (PCBM) as the p-type material prepared via the spin-coating method. The purpose of this study is to investigate the dependence of polymer solar cells’ performance on the concentration of Sb2S3 nanocrystals. The effect of the Sb2S3 nanocrystal concentrations (0.01, 0.02, 0.03, and 0.04 mg/mL) in the polymer’s active layer was determined using different characterization techniques. X-ray diffraction (XRD) displayed doped ratio dependences of P3HT crystallite orientations of P3HT crystallites inside a block polymer film. Introducing Sb2S3 NCs increased the light harvesting and regulated the energy levels, improving the electronic parameters. Considerable photoluminescence quenching was observed due to additional excited electron pathways through the Sb2S3 NCs. A UV–visible absorption spectra measurement showed the relationship between the optoelectronic properties and improved surface morphology, and this enhancement was detected by a red shift in the absorption spectrum. The absorber layer’s doping concentration played a definitive role in improving the device’s performance. Using a 0.04 mg/mL doping concentration, a solar cell device with a glass /ITO/PEDOT:PSS/P3HT-PCBM: Sb2S3:NC/MoO3/Ag structure achieved a maximum power conversion efficiency of 2.72%. These Sb2S3 NCs obtained by solvothermal fabrication blended with a P3HT: PCBM polymer, would pave the way for a more effective design of organic photovoltaic devices.

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