Near-field photoconductivity: Application to carrier transport in InGaAsP quantum well lasers

Buratto, Steven K.; Hsu, Julia W. P.; Betzig, Eric; Trautman, J. K.; Bylsma, R. B.; Bahr, C.C.; Cardillo, M. J.

doi:10.1063/1.112593

Cited by 65 publications

(27 citation statements)

References 13 publications

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“…It has to be mentioned that dimensions of the structures observed in the near-field PC images are certainly affected by the tip aperture, the penetration depth 1=a ¼ l=4pk of the light and by the subsequent diffusion of the excited carriers from the excitation volume [19]. In this sense we interpret the fact that the dimensions of the boron clusters, as observed in the near-field PC images, are about one order magnitude larger than those reported in Ref.…”

Section: Resultscontrasting

confidence: 43%

Near-Field Imaging of the Photocurrent Induced by Light on Boron-Implanted Silicon

Marocchi

Cricenti

Perfetti

et al. 2001

phys. stat. sol. (a)

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We report near-field photocurrent (PC) measurements performed on boron-implanted silicon and acquired at l ¼ 633; 1330; 1550 nm corresponding to photon energies of 1.96, 0.93, and 0.80 eV, respectively. The second and the third energies are below the silicon energy gap (E gap ¼ 1:12 eV), representing incident radiation to which Si is virtually transparent. The PC images acquired at l ¼ 1330 and 1550 nm reveal the presence of boron clusters which are a consequence of B-implantation and rapid thermal annealing at 1100 C. Boron clusters behave as metal clusters embedded into the silicon matrix and introduce gap states which give rise to the observed photocurrent. At energies larger than the Si energy gap the near-field PC images give information about subsurface defects not related to boron and with no correspondence in the surface topography.

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Section: Resultscontrasting

confidence: 43%

Near-Field Imaging of the Photocurrent Induced by Light on Boron-Implanted Silicon

Marocchi

Cricenti

Perfetti

et al. 2001

phys. stat. sol. (a)

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“…[8,10] NPC methods were first demonstrated by Buratto et al in the study of InGaAsP quantumwell lasers, [11] and later applied to stretch-oriented films of poly(p-phenylene vinylene) (PPV), [12] and more recently to poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) and (6,6)-phenyl C 61 -butyric acid (PCBM) blends. [13] In organic semiconductors, illumination with a nearfield optical source generates bound hole-electron pairs, or excitons, that can be separated into uncorrelated charge carriers with the help of either a built-in or externally applied electric field.…”

Section: Introductionmentioning

confidence: 99%

Local Probing of Photocurrent and Photoluminescence in a Phase‐Separated Conjugated‐Polymer Blend by Means of Near‐Field Excitation

Riehn

Stevenson

Richards

et al. 2006

Adv Funct Materials

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In this paper scanning near‐field microscopy is used to characterize polymer blends for photovoltaic applications, and fluorescence imaging and photoconductivity are combined to elucidate the spatial distribution and relative efficiency of current generation and photoluminescence in different domains of compositionally heterogeneous films. Focus is placed on a binary system consisting of poly[(9,9‐dioctylfluorene)‐alt‐benzothiadiazole] (F8BT) and poly[(9,9‐dioctylfluorene)‐alt‐(bis(N,N′‐(4‐butylphenyl))‐bis(N,N′‐phenyl‐1,4‐phenylenediamine))] (PFB), spun from xylene solutions, so as to obtain phase separation on micrometer and nanometer length scales. Protruding regions with diameters of about 5 μm in the topography image coincide with regions of high photocurrent (PC) and luminescence; these regions are identified as being F8BT‐rich. A general method to estimate the photoluminescence efficiency in the different domains of phase‐separated blends is proposed. As expected, lack of enhancement of the PC signal at the boundaries between protruding and lower‐lying phases indicate that these microscale boundaries play a small role in the charge generation by exciton splitting. This is consistent with the domains compositional inhomogeneity, and thus with finer phase separation within the domains. We also provide an analysis of the extent to which the metallized probe perturbs the near‐field photocurrent signal by integrating Poisson's equation. Finally, by using a Bethe–Bouwkamp model, the energy absorbed by the polymer film in the different regions is estimated.

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“…In addition, the spin lifetime for the higher-energy spin-up state was lower than the In addition to probing the luminescence properties of quantum structures, transport properties of these materials can also be probed using near-field photoconductivity (NPC) or near-field photovoltage (NPV). These near-field photoresponse techniques have been applied to a wide variety of heterostructures including graded Ge,Sil -JSi thin films (Hsu et al, 1994;, GaAs/AlGaAs heterostructures and InGaAsP quantum-well lasers (Buratto et al, 1994a) NPV of graded Ge,Sil-,/Si thin films (Hsu et al, 1994; performed at room temperature established a strong correlation between small depressions in the surface topography and threading dislocations which appear as dark spots in the NPV image as seen in Fig. 5.…”

Section: Nsom Of Quantum Wells and Quantum Wiresmentioning

confidence: 88%

Near-field scanning optical microscopy of nanostructures

1999

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The applications of near-field scanning optical microscopy (NSOM) to various nanostructured materials are reviewed. The review begins with a description of experimental aspects of NSOM and the various contrast mechanisms available with the technique. Applications of NSOM to a variety of different materials are then addressed including: NSOM of semiconductor heterostructures, NSOM of polymers and molecular crystals, and NSOM of Langmuir-Blodgett films and layered organic self-assemblies.

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Near-field photoconductivity: Application to carrier transport in InGaAsP quantum well lasers

Cited by 65 publications

References 13 publications

Near-Field Imaging of the Photocurrent Induced by Light on Boron-Implanted Silicon

Near-Field Imaging of the Photocurrent Induced by Light on Boron-Implanted Silicon

Local Probing of Photocurrent and Photoluminescence in a Phase‐Separated Conjugated‐Polymer Blend by Means of Near‐Field Excitation

Near-field scanning optical microscopy of nanostructures

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