Transient photocurrent induced in gallium nitride by two-photon absorption

Miragliotta, Joseph A.; Wickenden, D. K.

doi:10.1063/1.116891

Cited by 27 publications

(9 citation statements)

References 11 publications

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“…In another study, Miragliotta and Wickenden obtained a TPA coefficient of 1.5 cm/GW by twophoton-induced photocurrent spectroscopy, which is almost the same as the present measurement around E g /2 [9]. In contrast, TPA coefficients below E g /2 are negligible in photocurrent measurements.…”

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confidence: 66%

Efficient two‐photon absorption of bulk GaN in the near‐infrared region

Toda

Matsubara

Morita

et al. 2003

phys. stat. sol. (c)

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Transient transmission changes in the yellow luminescence (YL) band of GaN were investigated using excitation far smaller than the bandgap. At lower excitation power, time-resolved measurements revealed efficient transmission changes due to two-photon absorption (TPA), whose spectrum clearly indicates the contribution of the YL band. Upon increasing the excitation power, the transient signal showed an additional offset signal. The excitation power dependences of the offset suggested a two-step absorption process in conjunction with TPA in the YL band. The excitation energy dependence also supported this conclusion.The study of defect states in GaN films is important for understanding the device physics because even a device grade sample involves a high density of defects. One optical characteristic concerning the defect states is the so-called "yellow luminescence" (YL). So far, several research groups have obtained two-photon and multiple-photon related optical nonlinearities connected with the YL band. . In addition to the study of defect states, these nonlinear absorption studies also provide important insights into the fundamental physics of materials, such as band structures [1], relaxation processes [3-6], and electron-phonon interactions [7]. However, the role of the YL band in these optical nonlinearities remains largely unclear.In this paper, we investigate TPA in the YL band. Transient pump-probe measurements in the nearinfrared (NIR) excitation reveal efficient transmission changes, despite the lack of a bandgap transition. The TPA spectrum clearly shows that the observed large nonlinearity originates from the YL band. In addition, transmission changes at higher excitation power show an additional asymmetrical offset signal. The offset also reflects the characteristic of efficient TPA in the YL band.The sample studied was a freestanding bulk GaN sample with a thickness of $420 mm. The absence of a substrate allows the nonlinear response to be evaluated precisely. The electron concentration in the sample was estimated to be $ 10 19 cm À3 . A mode-locked Ti : sapphire laser (pulse width $100 fs, repetition rate 76 MHz) was employed as an NIR excitation light source. The tunable wavelength of the laser was 1.25 to 1.77 eV, which covers the excitation of carriers from the middle of the YL band to the middle of the energy gap (E G /2) into the conduction band. Linearly polarized pump

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supporting

confidence: 66%

Efficient two‐photon absorption of bulk GaN in the near‐infrared region

Toda

Matsubara

Morita

et al. 2003

phys. stat. sol. (c)

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“…2 In contrast, TPA coefficients below E g /2 are negligible in photocurrent measurements. In photocurrent spectroscopy, because only free carriers can contribute to the signal, it seems reasonable that TPA in the YL band is negligible.…”

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confidence: 99%

“…1 Recently, the optical nonlinearities of these materials have attracted increased interest as factors for determining device performance. [2][3][4][5][6][7][8][9][10][11] In addition to the technological importance, these nonlinear absorption studies also provide important insights into the fundamental physics of materials, such as band structures, 6 relaxation processes, [7][8][9][10] and electron-phonon interactions. 11 One characteristic of GaN observed in photoluminescence ͑PL͒ spectra is yellow luminescence ͑YL͒.…”

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confidence: 99%

Two-photon absorption and multiphoton-induced photoluminescence of bulk GaN excited below the middle of the band gap

Toda

Matsubara

Morita

et al. 2003

Applied Physics Letters

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Optical nonlinearity in the yellow luminescence (YL) band of GaN was investigated using thick bulk samples. Transient pump–probe measurements revealed strong transmission changes due to two-photon absorption(TPA) even at the middle of the YL band. The TPA coefficient evaluated reaches ∼5 cm/GW∼5 cm/GW at about 1.3 eV, which was as large as the mid-gap resonance. The TPA spectrum clearly showed that the observed large nonlinearity originated from the YL band. On the basis of efficient TPA in the YL band, relaxation processes in the multiphoton-induced photoluminescence excitation spectrum were also investigated

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“…The peak amplitude increases with the increase of exciting beam intensity. Because the incident intensity is about 10 6 W/cm 2 , at this intensity the three-and higher order multi-photon absorption could be neglected comparing to the photo-assistant twophoton absorption [4] . The free carrier absorption is about 10 -6 magnitude smaller than TPA in the top contact layer under the irradiation intensity over the wavelengths studied, thus the influence of free carrier absorption on TPA could be neglected.…”

Section: Resultsmentioning

confidence: 99%

The dispersion dependence of nonlinear optical absorption transition in silicon PIN photodiode

Cui

Qian

et al. 2013

2013 13th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)

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Abstract-This paper presents an experimental study on the dispersion dependence of two-photon absorption (TPA) between 0.689~0.912 eV in a Si-base PIN photodiode. The obvious TPA process is clearly observed as the nonlinear enhancement of peak photoresponse on the incident light intensity in the power of 2. The tendency of the TPA coefficient increases with the incident photon energy increasing. The maximum enhancement factor of the TPA coefficient has been achieved as high as 4 times. This dispersion dependence of TPA has been qualitatively interpreted as when the photon energy increases, the electrons of valance band excited by TPA find an increasing availability states of conduction band by phonon assistance.

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Transient photocurrent induced in gallium nitride by two-photon absorption

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Cited by 27 publications

References 11 publications

Efficient two‐photon absorption of bulk GaN in the near‐infrared region

Efficient two‐photon absorption of bulk GaN in the near‐infrared region

Two-photon absorption and multiphoton-induced photoluminescence of bulk GaN excited below the middle of the band gap

The dispersion dependence of nonlinear optical absorption transition in silicon PIN photodiode

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