Relation between photoreflectance excitation and absorption spectra for GaAs and GaN films

Behn, U.; Brandt, O.; Grahn, H. T.

doi:10.1063/1.1529290

Cited by 5 publications

(3 citation statements)

References 15 publications

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“…where η is an ideality factor, k b is the Boltzmann constant, J p and J o are the photocurrents due to the pump and probe beams, respectively, and J res is the restoring current [23]. The photovoltage is generally linear in the pump intensity provided the photo-injection is small with respect to the restoring current [32,33].…”

Section: Theoretical Principlesmentioning

confidence: 99%

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Z-scanning laser photoreflectance as a tool for characterization of electronic transport properties

Chism¹

2018

Journal of Applied Physics

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The physical principles motivating the Z -scanning laser photoreflectance technique are discussed.The technique is shown to provide a powerful non-contact means to unambiguously characterize electronic transport properties in semiconductors. The technique does not require modeling of charge transport in the sample or a detailed theoretical model for the sample physics. Rather, the measurement protocol follows directly from the simple relation describing the radial diffusion of carriers injected by a laser source. The use of a probe laser beam permits an analytic parameterization for the Z dependence of the photoreflectance signal which depends soley on the focal parameters and the carrier diffusion length. This allows electronic transport properties to be determined with high precision using a nonlinear least squares fit procedure. The practical use of the technique is illustrated by the characterization of carrier transport properties in semiconducting p-n junctions. *

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Section: Theoretical Principlesmentioning

confidence: 99%

“…Other considerations such as pump beam wavelength, intensity, and modulation frequency are also important [23][24][25]. This is due to the fact that the variations in physical quantities appearing in the r.h.s.…”

Section: Introductionmentioning

confidence: 99%

Z-scanning laser photoreflectance as a tool for characterization of electronic transport properties

Chism¹

2018

Journal of Applied Physics

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“…This method has been already successfully applied to quantum well structures or bulklike materials a few times, and it has been proved that it probes the optical transitions in a similar way as PLE and can be used to determine the modulation mechanisms. 17,18 Here, we demonstrate its applicability for investigation of QD structures as well and we show that the main factor responsible for PR response from self-assembled QDs is the photomodulation of the surface electric field.…”

Section: Introductionmentioning

confidence: 99%

On the modulation mechanisms in photoreflectance of an ensemble of self-assembled InAs∕GaAs quantum dots

Motyka

Sęk

Kudrawiec

et al. 2006

Journal of Applied Physics

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We present the investigation of the modulation mechanisms in photoreflectance (PR) spectroscopy of an ensemble of self-assembled semiconductor quantum dots (QDs). In order to distinguish between possible factors contributing to the total modulation efficiency of QD transitions, a photoreflectance excitation experiment has been performed on an InAs∕GaAs quantum dot structure grown by solid-source molecular beam epitaxy. It has been observed that the intensity of PR features related to QDs changes in a function of the wavelength of the pumping laser, tuned from above-GaAs band gap down to below wetting layer ground state transition. Based on this dependence we have shown that most of the QD PR signal intensity originates from the modulation of the built-in electric field caused by carriers photogenerated in GaAs layers. We also conclude that the modulation of QD transitions related to a possible modification of the dot properties due to filling them with carriers is negligible in PR experiment on an ensemble of dots. An additional confirmation of the PR results has been obtained by using contactless electroreflectance (CER), demonstrating that the line shape of PR and CER QD resonances is almost identical in both spectra. Thus, the QD transitions can be analyzed by using the standard low field line shape functional form applicable in any electromodulation spectroscopy.

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Fast measurements of photoreflectance spectra by using multi‐channel detector

Kudrawiec

Khachapuridze

Cywiński

et al. 2009

Physica Status Solidi (a)

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Photoreflectance (PR) measurements were performed on GaAs‐ and GaN‐based structures in the so called ‘bright configuration’ where the sample was illuminated by white light (probing beam) instead of monochromatic light as it takes place in the standard configuration, i.e., so‐called ‘dark configuration’. Within this concept the whole PR spectrum can be measured/processed at the same time using a multi‐channel detector (i.e., CCD camera) instead the phase sensitive lock‐in detection system with the one‐channel detector. In this work PR spectra for Si δ‐doped GaAs structure have been measured using both the CCD detector system as well as the standard lock‐in technique with the one‐channel detector system. GaAs‐related Franz–Keldysh oscillations, which are typical of Si δ‐doped GaAs structure, have been clearly observed in PR spectra measured by using the two detection systems. In addition, the PR system with the CCD detector has been used to measure PR spectra in the UV spectral region for an InGaN/GaN/Al2O3 structure. In this case, PR resonances related to InGaN and GaN band gap absorption have been clearly observed. Using the PR system with CCD detector the time of PR measurements was reduced to few seconds for both GaAs‐ and GaN‐based structures. It shows that the bright configuration of PR set‐up with multi‐channel detection system is very promising and perspective in the fast diagnostic of semiconductor structures. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Relation between photoreflectance excitation and absorption spectra for GaAs and GaN films

Cited by 5 publications

References 15 publications

Z-scanning laser photoreflectance as a tool for characterization of electronic transport properties

Z-scanning laser photoreflectance as a tool for characterization of electronic transport properties

On the modulation mechanisms in photoreflectance of an ensemble of self-assembled InAs∕GaAs quantum dots

Fast measurements of photoreflectance spectra by using multi‐channel detector

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