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Ewart, M.; Biaggio, Ivan; Zgonik, M.; Günter, Peter

doi:10.1103/physrevb.49.5263

Cited by 23 publications

(13 citation statements)

References 24 publications

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“…In a first attempt, HTOF in drift mode was applied with a continuous wave detection of the evolving space-charge field, but the low amount of probe-beam photons diffracted by the space-charge field, and the limited time response of the photomultiplier used to detect them, complicated the analysis [29]. These problems can be avoided by replacing the continuous wave detection by an appropriately time-delayed probe pulse in a pump and probe setup [14,15,20]. This was done in Ref.…”

Section: Review Of Mobility Investigations Performed Using Htofmentioning

confidence: 98%

“…In Ref. [15], the HTOF measurements were extended towards shorter spatial modulations and applied to several samples with different doping. The risetime data in Ref.…”

Section: Review Of Mobility Investigations Performed Using Htofmentioning

confidence: 99%

“…This effect is exploited by diffusion-mode HTOF [20], although this name was not used initially [14,15]. This technique is represented schematically in Figure 3.…”

Section: Introductionmentioning

confidence: 99%

“…the spatial period of the photoexcited charge pattern, is long and the mobility is small, charge-transport can be observed using a continuous wave probe beam. For short transport lengths -which can be as small as a fraction of a micrometer -and for larger mobilities, charge migration can be followed using a delayed probe pulse in a pump & probe fourwave mixing set-up [14,15,20] (see Figure 1). This allows the contact-less observation of charge-displacement with picosecond time resolution -from nanoseconds down to the duration of the optical pulses used -and the measurement of the charge-carrier mobility during the first few pico-or nanoseconds after photoexcitation, over transport lengths of one micrometer or less, before the first trapping event takes place.…”

Section: Introductionmentioning

confidence: 99%

“…When the spatial modulation period of the carrier distribution is small enough, the build-up time τ 0 corresponds to the carrier diffusion time and gives the mobility. Diffusion-mode HTOF was first used in a pump & probe, degenerate four wave mixing set-up to determine the intrinsic electron mobility in KNbO 3 [14,15].…”

Section: Introductionmentioning

confidence: 99%

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Holographic Time of Flight

Biaggio

Photo-Excited Processes, Diagnostics and Applications

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The Holographic Time of Flight (HTOF) method for the all-optical, contact-less investigation of charge transport in non-centrosymmetric insulators and semiconductors is based on the instantaneous photoexcitation of a spatially modulated distribution of charge carriers and on the linear electro-optic (Pockels) effect to visualize a charge-displacement by its associated refractive index change. It can be used with a free-carrier density so low that it does not otherwise have any detectable influence on the optical properties of a material, and with short free carrier lifetimes of the order of nanoseconds or less. HTOF is an especially striking example of how several independent linear and nonlinear light-matter interaction mechanisms can join to deliver a peculiar wave-mixing effect that is directly determined by a seemingly unrelated microscopic parameter: the free-carrier mobility. This chapter reviews the HTOF method and provides a detailed theoretical treatment that will be invaluable to experimentalists interested in applying this method to new materials. The author discusses the experimental parameters that influence the HTOF results and presents the basic assumptions and experimental conditions that allow the characterization of charge transport in the bulk of a material, with a sub-nanosecond time resolution only limited by the duration of the laser pulses, and for transport lengths down to a fraction of a micrometer. IntroductionBy illuminating a dielectric material with a pulsed laser it is possible to optically excite free electrons or holes, either from donor centers in the energy band gap between valence and conduction band, or directly by interband transitions. This leads to a transient increase in the number of free charge carriers, and therefore of the conductivity. Transient studies of current initiated by optical excitation of charge carriers lead to several ways to study charge transport processes in insulators and semiconductors.Homogenous charge-carrier photoexcitation in the bulk of a sample can be achieved by photoionization of impurity centers with energy levels inside the energy band gap. The analysis of such a homogenous photoconductivity transient gives some information on the charge transport properties, but generally delivers only indirect information on the charge-carrier mobility.On the other hand, the optical excitation of a packet of charges localized at the surface of a sample, either by interband excitation or by charge-carrier injection, is at the basis of conceptually simple methods to measure drift mobilities [1]. These methods rely on the observation of the drift of a charge-carrier packet in an applied electric field by its controlled photoexcitation and the detection of its time-of-arrival after a well-defined transport length. A well-established tool to CHAPTER 4

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Section: Review Of Mobility Investigations Performed Using Htofmentioning

confidence: 98%

“…In Ref. [15], the HTOF measurements were extended towards shorter spatial modulations and applied to several samples with different doping. The risetime data in Ref.…”

Section: Review Of Mobility Investigations Performed Using Htofmentioning

confidence: 99%

“…This effect is exploited by diffusion-mode HTOF [20], although this name was not used initially [14,15]. This technique is represented schematically in Figure 3.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Pulsed-photoexcitation studies in photorefractiveKNbO3

Cited by 23 publications

References 24 publications

Holographic Time of Flight

Holographic Time of Flight

Introduction

Recording Speed and Determination of Basic Materials Properties

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