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

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.

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

2012 ◽  
Vol 717-720 ◽  
pp. 305-308 ◽  
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.

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.

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

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.

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

2007 ◽  
Vol 46 (8A) ◽  
pp. 5057-5061 ◽  
Author(s):  
Masashi Kato ◽  
Masahiko Kawai ◽  
Tatsuhiro Mori ◽  
Masaya Ichimura ◽  
Shingo Sumie ◽  
...  
Keyword(s):  
Carrier Lifetime ◽  
Excess Carrier ◽  
Photoconductivity Decay ◽  
P Type ◽  
Sic Wafer

Excess carrier lifetime of 3C–SiC measured by the microwave photoconductivity decay method

1997 ◽  
Vol 70 (13) ◽  
pp. 1745-1747 ◽  
Author(s):  
M. Ichimura ◽  
H. Tajiri ◽  
Y. Morita ◽  
N. Yamada ◽  
A. Usami
Keyword(s):  
Carrier Lifetime ◽  
Excess Carrier ◽  
Photoconductivity Decay

Effect of Surface and Interface Recombination on Carrier Lifetime in 6H-SiC Layers

2013 ◽  
Vol 740-742 ◽  
pp. 490-493
Author(s):  
Jian Wu Sun ◽  
Satoshi Kamiyama ◽  
Rositza Yakimova ◽  
Mikael Syväjärvi
Keyword(s):  
Diffusion Coefficient ◽  
Numerical Simulations ◽  
Carrier Lifetime ◽  
Surface Recombination ◽  
Experimental Results ◽  
Surface And Interface ◽  
Carrier Lifetimes ◽  
Interface Recombination ◽  
Photoconductivity Decay ◽  
Effect Of Surface

Carrier lifetimes in 6H-SiC epilayers were investigated by using numerical simulations and micro-wave photoconductivity decay measurements. The measured carrier lifetimes were significantly increasing with an increased thickness up to 200 μm while it stays almost constant in layers thicker than 200 μm. From a comparison of the simulation and experimental results, we found that if the bulk lifetime in 6H-SiC is around a few microseconds, both the surface recombination and interface recombination influence the carrier lifetime in layers with thickness less than 200 μm while only the surface recombination determines the carrier lifetime in layers with thickness more than 200 μm. In samples with varying thicknesses, a bulk lifetime = 2.93 μs and carrier diffusion coefficient D= 2.87 cm2/s were derived from the linear fitting of reciprocal lifetime vs reciprocal square thickness.

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.

Passivation of Silicon Surfaces Using Atomic Layer Deposited Metal Oxides

2009 ◽  
Vol 1153 ◽  
Author(s):  
Jun Wang ◽  
Mahdi Farrokh Baroughi ◽  
Mariyappan Shanmugam ◽  
Roohollah Samadzadeh-Tarighat ◽  
Siva Sivoththaman ◽  
...  
Keyword(s):  
Carrier Lifetime ◽  
Surface Passivation ◽  
Atomic Layer ◽  
Silicon Surfaces ◽  
Silicon Substrates ◽  
Excess Carrier ◽  
Si Substrates ◽  
Layer Deposition ◽  
Deposited Metal ◽  
Photoconductivity Decay

AbstractSurface passivation of silicon substrates using atomic layer deposited Al2O3 and HfO2 thin films are assessed. Al2O3 and HfO2 dielectric layers with various thicknesses were deposited on both sides of n-type (100) FZ-Si substrates (resistivity 4 – 6 Ω-cm) at 200°C by atomic layer deposition (ALD) system. The effective excess carrier lifetime of as-deposited oxide/Si/oxide structure was measured by microwave-photoconductivity-decay (MWPCD) measurement technique and it was observed that the thicker ALD dielectrics lead to higher effective excess carrier lifetime and better surface passivation. The measurements showed average excess carrier lifetime values of 302 μs and 347 μs for as-deposited Al2O3 and HfO2 passivated Si substrates with 150 ALD cycles, respectively. MWPCD and capacitance-voltage (C-V) measurements suggest that as-deposited ALD HfO2 layer leads to a better surface passivation compared to as-deposited ALD Al2O3 layer. Further, the results suggest that there exist fixed negative charges in the bulk of the ALD dielectrics and this contributes to the field effect passivation of the silicon surfaces.

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

Microsecond Carrier Lifetimes in Bulk-Like 3C-SiC Grown by Sublimation Epitaxy

2013 ◽  
Vol 740-742 ◽  
pp. 315-318
Author(s):  
Jian Wu Sun ◽  
Satoshi Kamiyama ◽  
Peter J. Wellmann ◽  
Rickard Liljedahl ◽  
R. Yakimova ◽  
...  
Keyword(s):  
High Resolution ◽  
Carrier Lifetime ◽  
Crystal Quality ◽  
Injection Level ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Carrier Lifetimes ◽  
Photoconductivity Decay

High quality bulk-like 3C-SiC were grown on on-axis (0001) 6H-SiC substrate by sublimation epitaxy. The microwave photoconductivity decay mapping measurements revealed that this material shows considerable long carrier lifetimes varied from 3.519 to 7.834 μs under the injection level of 3.5×1012 cm-2, which are comparable with the best carrier lifetimes in 4H-SiC layers. The mapping of high resolution x-ray diffraction obtained from the same region shows that smaller carrier lifetimes seem to correspond to the larger FWHM values and vice versa. This shows that long carrier lifetime obtained in 3C-SiC is due to the improvement of the crystal quality.

Sign in / Sign up

Export Citation Format

Share Document