The diffraction of light by transient gratings in crystalline, ion-implanted, and amorphous silicon

Vaitkus, J.; Jarašiūnas, K.; Gaubas, E.; Jonikas, L.; Pranaĭtis, R V; Subačius, L.

doi:10.1109/jqe.1986.1073129

Cited by 38 publications

(19 citation statements)

References 16 publications

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“…The grating decay is single exponential at T = 100 K, while at lower temperatures the kinetics become non-exponential and reveal contribution of another mechanism of refractive index modulation. We attribute this effect to refractive index modulation by temperature, previously observed in Si and 4H-SiC [14,15]. We have found that the contribution of coexisting temperature grating in 3C-SiC is increasing at lower temperature (Fig.…”

Section: Resultssupporting

confidence: 70%

Characterization of SiC crystals by optical and electrical means

Neimontas¹

2008

Lithuanian J. Phys

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Measurements of carrier transport have been carried out in different SiC polytypes by using two complementary techniques: a picosecond four-wave mixing and magnetoresistance. Both techniques confirmed the mechanism of phonon scattering in T = 100-300 K range, as well as higher carrier mobility in n-type 4H epitaxial layers with respect to 3C-SiC. The optical technique revealed a decrease of the bipolar mobility in 3C-SiC at T < 100 K and its variation with photoexcited carrier density. A lattice heating was observed in free standing 3C-and 4H-SiC due to strong impact of nonradiative recombination, and this effect precluded optical studies of carrier dynamics at low temperatures.

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Section: Resultssupporting

confidence: 70%

Characterization of SiC crystals by optical and electrical means

Neimontas¹

2008

Lithuanian J. Phys

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“…At lower temperatures, the kinetics become non-exponential and reveal competition with another mechanism of refractive index modulation. We attribute this effect to refractive index modulation by temperature ∆n T , previously observed in highly excited Si crystals [7]. We have found that the contribution of coexisting temperature grating in SiC is increasing at lower temperature, and diffraction efficiency of it is comparable with that of free carrier grating.…”

Section: Resultssupporting

confidence: 69%

“…Assuming the high photoexcited carrier density, quantum excess energy (hν − E g ), and the mechanism of nonradiative recombination in SiC, a local heating of the sample must be taken into account. It is known that the thermal refractive index modulation ∆n T = ∂n/∂T · T (x, t) can emerge in highly excited Si crystals [7,8]. The temperature distribution T (x, t) in the silicon carbide sample is described by the following equation:…”

Section: Experimental Techniquementioning

confidence: 99%

“…Here the terms on the right side are the sources of heat generation due to Auger recombination, free-carrier absorption, and overload of E g , ρ is the density of SiC, C p is the specific heat, σ eh is the cross-section of free carrier absorption, and D T is the thermal diffusion coefficient [7]. The total refractive index modulation is due to polarizability by electron-hole pairs ∆n FC and to the temperature change ∆n T ,…”

Section: Experimental Techniquementioning

confidence: 99%

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Temperature-dependent nonequilibrium carrier dynamics in epitaxial and bulk 4H-SiC

Neimontas¹

2006

Lithuanian J. Phys.

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We present the results of nonequilibrium carrier dynamics in highly excited 4H-SiC crystals -n-type epilayers and semiinsulating wafer. Picosecond four-wave mixing measurements have been carried out at various grating periods, excitation energies, temperatures, and have provided the bipolar diffusion coefficients and lifetimes of nonequilibrium carriers. We show that the phonon scattering contributes mainly to the carrier mobility in 100-300 K temperature range, providing µ ∼ T −1.5 dependence. Lattice heating was observed, and it dominated in refractive index modulation at T < 100 K, thus precluding the studies of carrier dynamics at low temperatures.

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“…Most of the previous studies used band-to-band bipolar carrier plasma generation to create free carriers in Si, Ge, A,B,, A,B, compounds by one-or two-photon absorption of light. Time resolved grating decay measurements of the characteristics of the self-diffracted beam intensity revealed carrier diffusion and recombination processes in pure crystals, carrier generation, and transport peculiarities due to doping by shallow impurities, ion irradiation, external electric fields [4]. Possible applications of this technique in the fields of material research have been shown [5].…”

Section: Introductionmentioning

confidence: 97%

Optical Nonlinearities and Carrier Transport in GaAs: EL2 at High Excitation Levels

Jarašiūnas

Delaye

Roosen

1993

Physica Status Solidi (b)

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Laser induced picosecond transient gratings are used to study carrier transport via free carrier and photorefractive nonlinearities in semi-insulating undoped GaAs bulk crystals. Carrier lifetime ( T~ = 1.5 ns), hole and ambipolar mobilities (ph = 410 cm2 V-' s-' , pa = 760cm2V-'s-') are measured directly and an electron mobility equal to 5200 cm2 V -' s -' is calculated. The optical properties of highly excited GaAs reveal deep donor EL2 transformation and intracenter absorption under picosecond excitation. Rotation of the diffracted beam polarization is observed for the first time in orientation of the grating vector along the crystallographic axis [OOl]. This signal is attributed to a strain field at dislocations in LEC-grown GaAs wafers.La diffraction de la lumiere sur les reseaux de porteurs libres et photortfractif engendrts par des impulsions picoseconde permet d'etudier les non-lintaritbs optiques ainsi que le transport des porteurs libres dans le GaAs semi-isolant. Le temps de vie (7R = 1,5 ns), la mobilitk des trow et la mobilite ambipolaire (ph = 410 cmz V-' s-l , pa = 760 cmz V-' s-') sont mesuries directement; la valeur de la mobilitd des electrons en est deduite (p, = 5200 cm2 V-' s-' ). Les proprietbs optique du GaAs sous fortes excitations rkvelent les transformations du niveau profond EL2 et I'absorption intracentre sous excitation picoseconde. Une rotation de la polarisation du faisceau diffracte est observee pour la premiere fois avec un vecteur reseau oriente suivant I'axe cristallographique [Ool]. Ce signal est attribut a un champ de contrainte a longue distance autour des dislocations dans le GaAs fabrique par la technique LEC.

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The diffraction of light by transient gratings in crystalline, ion-implanted, and amorphous silicon

Cited by 38 publications

References 16 publications

Characterization of SiC crystals by optical and electrical means

Characterization of SiC crystals by optical and electrical means

Temperature-dependent nonequilibrium carrier dynamics in epitaxial and bulk 4H-SiC

Optical Nonlinearities and Carrier Transport in GaAs: EL2 at High Excitation Levels

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