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

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.

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Excess Carrier Lifetime in a Bulk p-Type 4H–SiC Wafer Measured by the Microwave Photoconductivity Decay Method

Japanese Journal of Applied Physics ◽

10.1143/jjap.46.5057 ◽

2007 ◽

Vol 46 (8A) ◽

pp. 5057-5061 ◽

Cited By ~ 18

Author(s):

Masashi Kato ◽

Masahiko Kawai ◽

Tatsuhiro Mori ◽

Masaya Ichimura ◽

Shingo Sumie ◽

...

Keyword(s):

Carrier Lifetime ◽

Excess Carrier ◽

Photoconductivity Decay ◽

P Type ◽

Sic Wafer

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Correlation between Strain and Excess Carrier Lifetime in a 3C-SiC Wafer

Materials Science Forum ◽

10.4028/www.scientific.net/msf.717-720.305 ◽

2012 ◽

Vol 717-720 ◽

pp. 305-308 ◽

Cited By ~ 1

Author(s):

Atsushi Yoshida ◽

Masashi Kato ◽

Masaya Ichimura

Keyword(s):

Raman Spectroscopy ◽

Optical Microscopy ◽

Carrier Lifetime ◽

Structural Defects ◽

Free Standing ◽

Excess Carrier ◽

Carrier Lifetimes ◽

Photoconductivity Decay ◽

Sic Wafer

We obtained excess carrier lifetime maps by the microwave photoconductivity decay (µ-PCD) method in a free-standing n-type 3C-SiC wafer, and then we compared the lifetime maps with distributions of strains and defects observed by the optical microscopy and the Raman spectroscopy. We found that the excess carrier lifetimes are short in a strained region in 3C-SiC, which indicates that structural defects exist around a strained region.

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

Materials Science Forum ◽

10.4028/www.scientific.net/msf.645-648.207 ◽

2010 ◽

Vol 645-648 ◽

pp. 207-210 ◽

Cited By ~ 6

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.

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Precise Measurements of Transient Excess Carrier Lifetimes in II-VI Films and Superlattices

MRS Proceedings ◽

10.1557/proc-161-217 ◽

1989 ◽

Vol 161 ◽

Author(s):

W. O. Doggett ◽

Michael W. Thelander ◽

J. F. Schetzina

Keyword(s):

Molecular Beam ◽

Statistical Data ◽

Laser Pulses ◽

Statistical Data Analysis ◽

Analysis Techniques ◽

Excess Carrier ◽

Carrier Lifetimes ◽

System A ◽

Transient Photoconductivity ◽

Photoconductivity Decay

ABSTRACTA system has been developed for accurately measuring lifetimes for photo-induced excess current carriers in semiconductors using the transient photoconductivity decay method. The specifications of state-of-the-art equipment, considerations peculiar to the capture of fast transient pulses, and sophisticated statistical data analysis techniques are discussed. Experimental results are presented to demonstrate the capability of the system (a) to measure lifetimes in the 40-ns - 75-µs range for temperatures varying from 77K to 300K with 10% accuracy for single lifetime decays and 30% accuracy for individual effective lifetimes in a multi-component decay, and (b) to use a 300-ns lifetime photoconductor as a detector to measure nanosecond-time-scale structure of laser pulses. The predominant excess carrier lifetimes of HgCdTe samples grown at NCSU by photoassisted molecular beam epitaxy (PAMBE) ranged from 46 ns at 300K to 341 ns at 77K. CdTe samples and CdMnTe-CdTe superlattices exhibited a multi-component decay with the two longest components having effective lifetimes of 26 µs and 4 µs for CdTe and 75 µs and 10 µs for CdMnTe-CdTe. These values were relatively insensitive to temperature variation.

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

Advances in Materials Science and Engineering ◽

10.1155/2021/5568880 ◽

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.

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Excess Carrier Lifetime Measurements for GaN on Sapphire Substrates with Various Doping Concentrations and Surface Conditions by the Microwave Photoconductivity Decay Method

MRS Proceedings ◽

10.1557/proc-831-e3.3 ◽

2004 ◽

Vol 831 ◽

Author(s):

Masashi Kato ◽

Hideki Watanabe ◽

Masaya Ichimura ◽

Eisuke Arai

Keyword(s):

Inductively Coupled Plasma ◽

Carrier Lifetime ◽

Surface Conditions ◽

Excess Carrier ◽

Carrier Lifetimes ◽

Sapphire Substrates ◽

Icp Etching ◽

Photoconductivity Decay ◽

Si Doped ◽

Mg Doped

ABSTRACTWe have measured excess carrier lifetimes in GaN with various doping concentrations and surface conditions by the microwave photoconductivity decay method. GaN samples were grown by metalorganic chemical vapor deposition (MOCVD) without intentional doping and with Si doping or Mg doping on a-face sapphire substrates. By using the microwave photoconductivity decay method, we obtained 1/e excess carrier lifetimes of larger than 50 μs for the Si doped and undoped GaN and of less than 10 μs for the Mg doped GaN. We changed surface conditions for the samples by the inductively coupled plasma (ICP) etching and investigated effects of surface conditions on the carrier recombination behavior. The ICP etching has negligible effects on carrier lifetime in the Si doped GaN. On the other hand, in the undoped GaN, the ICP etching lengthened the carrier lifetime compared with the as-grown sample. On the contrary, the ICP etching shortened the carrier lifetime in the Mg doped GaN. The ICP etching seems to form hole traps and recombination centers at GaN surfaces and thus the carrier lifetime became longer in the undoped GaN and shorter in the Mg doped GaN.

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The Excess Carrier Lifetime in P-Type HgCdTe Measured by Photoconductive Decay

10.1109/eeis.1989.720012 ◽

2005 ◽

Cited By ~ 2

Author(s):

R. Fastow ◽

Y. Nemirovsky

Keyword(s):

Carrier Lifetime ◽

Photoconductive Decay ◽

Excess Carrier ◽

P Type

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Surface Recombination Investigation in Thin 4H-SiC Layers

Materials Science ◽

10.5755/j01.ms.17.2.479 ◽

1970 ◽

Vol 17 (2) ◽

pp. 119-124 ◽

Cited By ~ 4

Author(s):

Karolis GULBINAS ◽

Vytautas GRIVICKAS ◽

Haniyeh P. MAHABADI ◽

Muhammad USMAN ◽

Anders HALLÉN

Keyword(s):

Surface Passivation ◽

Surface Recombination ◽

Atomic Layer ◽

Surface Recombination Velocity ◽

Lifetime Distributions ◽

Carrier Lifetimes ◽

Layer Deposition ◽

Type Layer ◽

Recombination Velocity ◽

P Type

n- and p-type 4H-SiC epilayers were grown on heavily doped SiC substrates. The thickness of the p-type layer was 7 µm and the doping level around 1017 cm 3, while the n-type epilayers were 15 µm thick and had a doping concentration of 3 - 5*1015 cm 3. Several different surface treatments were then applied on the epilayers for surface passivation: SiO2 growth, Al2O3 deposited by atomic layer deposition, and Ar-ion implantation. Using collinear pump - probe technique the effective carrier lifetimes were measured from various places and statistical lifetime distributions were obtained. For surface recombination evaluation, two models are presented. One states that surface recombination velocity (SRV) is equal on both the passivation/epi layer interface (S2) and the deeper interface between the epilayer and the SiC substrate i. e. (S1 = S2). The other model is simulated assuming that SRV in the epilayer/substrate (S1) interface is constant while in the passivation layer/epilayer (S2) interface SRV can be varied S2 < S1. Empirical nomograms are presented with various parameters sets to evaluate S2 values. We found that on the investigated 4H-SiC surfaces S2 ranges from 3x104 to 5x104 assuming that the bulk lifetime is 4 (µs. In Ar+ implanted surfaces S2 is between (105 - 106) cm/s.http://dx.doi.org/10.5755/j01.ms.17.2.479

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