Carrier lifetimes in silicon

Schroder, D.K.

doi:10.1109/16.554806

Cited by 401 publications

(247 citation statements)

References 26 publications

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“…The modulation rate of this STM is limited by the optical SLM which is 60 frames per second. Considering the recombination time (about 10 ms) of the photo-excited carries 27 , the modulation rate can arrive 10 5 frames per second if a suitable optical projector is used. Limited by the output power of our femtosecond laser source (about 800 mW) and the high loss of the optical SLM, the highest intensity of the control beam is only 16.4 mJ/cm 2 , the modulation depth is only 19.9%, which leads to a low diffraction efficiency about 0.2%.…”

mentioning

confidence: 99%

Spatial Terahertz Modulator

Xie

Wang

et al. 2013

Sci Rep

127

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Terahertz (THz) technology is a developing and promising candidate for biological imaging, security inspection and communications, due to the low photon energy, the high transparency and the broad band properties of the THz radiation 1-3 . However, a major encountered bottleneck is lack of efficient devices to manipulate the THz wave, especially to modulate the THz wave front. A wave front modulator should allow the optical or electrical control of the spatial transmission (or reflection) of an input THz wave and hence the ability to encode the information in a wave front 4 . Here we propose a spatial THz modulator (STM) to dynamically control the THz wave front with photo-generated carriers. A computer generated THz hologram is projected onto a silicon wafer by a conventional spatial light modulator (SLM). The corresponding photo-generated carrier spatial distribution will be induced, which forms an amplitude hologram to modulate the wave front of the input THz beam. Some special intensity patterns and vortex beams are generated by using this method. This all-optical controllable STM is structure free, high resolution and broadband. It is expected to be widely used in future THz imaging and communication systems.S andwiched between the microwave and infrared, THz radiation has been notoriously difficult to produce, modulate and detect [1][2][3] . Recent progresses such as quantum-cascade lasers 5,6 , terahertz wave generation through a nonlinear crystal 7 and THz time-domain spectroscopy 8 are promoting this subject into one of the most rapidly growing fields. High performance devices to control and manipulate the THz radiation are in urgent demand to develop sophisticated imaging and communication system. The filters, absorbers and polarizers based on graphene, frequency selective surface, metamaterials and photonic crystals have been reported [9][10][11][12][13][14][15][16][17][18] . However, the wave front modulation devices are still lacking. Recently, a novel technology based on the metasurface has been demonstrated to generate the desired wave front distribution 19,20 . Unfortunately, the specific function of this kind of devices has been determined at the moment of their design and could not be flexibly changed any more. The SLM which has been widely used in the visible light band can optically or electrically control the spatial transmission (or reflection) of an input light beam and encode information in the wave front 4 . The SLM always plays an important role in optical information processing, three dimensional image display, optical interconnections and real-time beam shaping. Usually, the SLM is realized through liquid crystals, magneto-optic materials or deformable mirrors. However, such mechanisms cannot work well in the THz regime due to the lack of suitable materials and the size mismatching between the micro-machined components and the THz wavelength 21 . In order to obtain the STM, a novel technology needs to be explored.The STM requires an array of small building blocks that can independentl...

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confidence: 99%

Spatial Terahertz Modulator

Xie

Wang

et al. 2013

Sci Rep

127

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“…The bulk lifetime and the surface recombination velocity do not depend on the pump wavelength but from (27) we can see that the instantaneous observed lifetime 0 depends on it. In particular, the dependence is all included in the initial part, while the asymptotic part is unaffected.…”

Section: Multiwavelength Methodmentioning

confidence: 91%

“…This avoids the measurements with the pump impinging one time on one surface and one time on the other surface, which can lead to some errors. Moreover the desired quantities are better and more accurately retrieved by fitting simultaneously a set of equations similar to (27), obtained, nevertheless, with a more accurate theoretical model of the best fit curve. The measurement is then performed from the a-priori knowledge of the other sample parameters involved, and allows for a better the determination of them.…”

Section: Cross-sectional Profilingmentioning

confidence: 99%

“…Anyway, without entering in detail, for which we refer to [8,[23][24][25][26][27], to define SRV we have to consider that, since the carriers that recombine at the surfaces of the sample can be described as a current-like flow outside the latest, it is much easier to model the presence of the recombination centers on the surface by means of appropriate boundary conditions that bind the values of the carriers concentration and its gradient at the boundaries. This leads to the following SRV definition:…”

Section: Surface Recombination Lifetime and Surfacementioning

confidence: 99%

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Optical Measurement Techniques of Recombination Lifetime Based on the Free Carriers Absorption Effect

Laurentis

Irace

2014

Journal of Solid State Physics

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We review successful measurement techniques for the evaluation of the recombination properties in semiconductor materials based on the optically induced free carrier absorption. All the methodologies presented share the common feature of exploiting a laser beam to excite electron-hole pairs within the volume of the sample under investigation, while the probing methods can vary according to the different methodology analyzed. As recombination properties are of paramount importance in determining the properties of semiconductor devices (i.e, bipolar transistor gain, power devices switching features, and solar cells efficiency), their knowledge allows for better understanding of experimental results and robust TCAD simulator calibration. Being contactless and applicable without any particular preparation of the sample under investigation, they have been considered attractive to monitor these parameters inline or just after production of many different semiconductor devices.

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“…Several lifetime measurement techniques have been studied [4][5][6], implying optical, or current excitations. As we want to characterize photodiodes, we have used the Open-Circuit-VoltageDecay (OCVD) method.…”

Section: Introductionmentioning

confidence: 99%