Polarization-Resolved Near-Field Spectroscopy of Localized States in 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>m</mml:mi></mml:math>
-Plane 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>In</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>Ga</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mi m

Ivanov, Ruslan; Marcinkevičius, Saulius; Mensi, Mounir; Martı́nez, O.; Kuritzky, Leah Y.; Myers, Daniel J.; Nakamura, Shuji; Speck, James S.

doi:10.1103/physrevapplied.7.064033

Cited by 16 publications

(10 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The emission is assumed to be inhomogeneously broadened due to contributions from material regions with different eigenenergies associated with fluctuations of the In content. Spatial variations of emission intensities and/or energies were previously observed in nitride semiconductor structures by far field [1] and near-field [2,3] photoluminescence microscopy or cathodoluminescence microscopy [4][5][6]. These observations have evidenced so far emitting domains of either micron or submicron (typically 100 nm) size.…”

mentioning

confidence: 90%

Evidence of nanoscale Anderson localization induced by intrinsic compositional disorder in InGaN/GaN quantum wells by scanning tunneling luminescence spectroscopy

et al. 2018

View full text Add to dashboard Cite

We present direct experimental evidences of Anderson localization induced by the intrinsic alloy compositional disorder of InGaN/GaN quantum wells. Our approach relies on the measurement of the luminescence spectrum under local injection of electrons from a scanning tunneling microscope tip into a near-surface single quantum well. Fluctuations in the emission line shape are observed on a few-nanometer scale. Narrow emission peaks characteristic of single localized states are resolved. Calculations in the framework of the localization landscape theory provide the effective confining potential map stemming from composition fluctuations. This theory explains well the observed nanometer scale carrier localization and the energies of these Anderson-type localized states. The energy spreading of the emission from localized states is consistent with the usually observed very broad photo-or electro-luminescence spectra of InGaN/GaN quantum well structures.InGaN quantum wells (QWs), the active regions of nitride-based LEDs, display broad photo-or electroluminescence spectra. The emission is assumed to be inhomogeneously broadened due to contributions from material regions with different eigenenergies associated with fluctuations of the In content. Spatial variations of emission intensities and/or energies were previously observed in nitride semiconductor structures by far field [1] and near-field [2, 3] photoluminescence microscopy or cathodoluminescence microscopy [4][5][6]. These observations have evidenced so far emitting domains of either micron or submicron (typically 100 nm) size. While significant energy shifts due to these rather large-scale fluctuations were observed, no linewidths below 100 meV at room temperature were detected. These large-scale luminescence fluctuations are usually associated with growth inhomogeneities seen for instance in AFM. However, in the case of random atom positioning in the alloy crystal [7], modeling predicts that the compositional disorder should induce Anderson localization in regions of a few nm size [8][9][10][11][12][13][14]. Moreover, emission from such single localized states is expected to exhibit a narrow linewidth of a few tens of meV at room temperature, i.e. comparable to what was observed from single GaN quantum dots [15]. Such emission features exhibiting size and spectroscopic signatures characteristic of carrier localization induced by the alloy disorder have not been evidenced up to now.Here we report on the observation of fluctuations in the luminescence spectrum on the scale of a few nm as expected for such localization effects. Our approach is based on scanning tunneling luminescence (STL) microscopy [16] which allows luminescence measurements under local carrier injection with a nm scale resolution. In order to reach the required spatial resolution, we used p-type single InGaN/GaN QW structures with a thin top GaN layer separating the QW from the injecting tip of the scanning tunneling microscope (STM) and we analyzed the spatial variations in the luminescence sp...

show abstract

mentioning

confidence: 90%

Evidence of nanoscale Anderson localization induced by intrinsic compositional disorder in InGaN/GaN quantum wells by scanning tunneling luminescence spectroscopy

et al. 2018

View full text Add to dashboard Cite

show abstract

“…This is evidenced by the large shift of 230 meV for the E⊥c PL peak for temperatures between 4 and 300 K [20], which is much larger than the shift of the GaN band gap (70 meV [31]). This difference indicates that the shift of the QW peak is primarily determined by the carrier redistribution between the localized states rather than by the band gap shrinkage.…”

Section: Polarization-resolved Snom For Studies Of Localized States Imentioning

confidence: 97%

“…The alloy composition may also experience lateral variations due to the presence of extended defects that induce the lateral strain variation [16,40]. Moreover, there have been suggestions that variations of the alloy composition may also be linked to the surface morphology, as shown for InGaN QWs [18][19][20]. Using SNOM, we investigate this effect in the InGaN layer.…”

Section: Spectrally-resolved Snom Applied On Ingan Epitaxial Layersmentioning

confidence: 99%

See 1 more Smart Citation

Multimode scanning near-field photoluminescence spectroscopy and its application for studies of InGaN epitaxial layers and quantum wells

Marcinkevičius¹,

Uždavinys²,

Ivanov³

et al. 2018

physics

Self Cite

View full text Add to dashboard Cite

The paper reviews our recent achievements in developing a multimode scanning near-field optical microscopy (SNOM) technique. The multimode SNOM apparatus allows us to simultaneously measure spatial variations of photoluminescence spectra in the illumination and illumination-collection modes, their transients and sample surface morphology. The potential of this technique has been demonstrated on a polar InGaN epitaxial layer and nonpolar InGaN/GaN quantum wells. SNOM measurements have allowed revealing a number of phenomena, such as the band potential fluctuations and their correlation to the surface morphology, spatial nonuniformity of the radiative and nonradiative lifetimes, as well as the extended band nature of localized states. The combination of different modes enabled measurements of the ambipolar carrier diffusion and its anisotropy.

show abstract

“…In addition to macroscopic photoluminescence (PL), nanoscopic spectroscopy with high spatial resolution is a powerful tool for evaluating potential fluctuations directly. PL mapping using scanning near‐field optical microscopy (SNOM‐PL) is a spatially resolved spectroscopy technique that has been used to assess potential fluctuations in polar InGaN epitaxial layers and QWs, nonpolar InGaN QWs, and semipolar InGaN QWs …”

Section: Introductionmentioning

confidence: 99%

Potential Barrier Formed Around Dislocations in InGaN Quantum Well Structures by Spot Cathodoluminescence Measurements

Kurai

Higaki

Imura

et al. 2017

Physica Status Solidi (b)

View full text Add to dashboard Cite

We carried out spot cathodoluminescence (CL) with scanning electron microscopy (SEM‐CL) of InGaN multiple quantum well (MQW) structures with an In molar fraction of 18% grown on c‐plane sapphire at room temperature, in which formation of a potential barrier around threading dislocations was confirmed in previous spatially resolved photoluminescence measurements with scanning near‐field optical microscopy (SNOM‐PL). We confirmed the suitability of CL measurements for evaluating the local potential barriers near the dislocations. Local emissions around the V‐pits were observed in monochromatic CL mapping images acquired at the higher‐energy side of InGaN emissions at RT and 78 K. The density of the higher‐energy emission regions was smaller than the V‐pit density, indicating the effect of nonradiative recombination. Spot CL spectra around the V‐pits showed shoulders on the higher‐energy side of the InGaN peaks. These observations agree with the SNOM‐PL results acquired from the same samples, indicating that SEM‐CL can be used to evaluate potential barriers. The emission energy difference between the InGaN and higher‐energy emissions estimated by spot CL spectra was compared with that estimated by SNOM‐PL spectra. The energy difference as a function of pit diameter showed a similar trend for both measurement methods, but was slightly smaller for the SEM‐CL results, suggesting that the potential barrier height evaluation is not necessarily quantitative.

show abstract

Polarization-Resolved Near-Field Spectroscopy of Localized States in m -Plane InxGa1−x

Cited by 16 publications

References 40 publications

Evidence of nanoscale Anderson localization induced by intrinsic compositional disorder in InGaN/GaN quantum wells by scanning tunneling luminescence spectroscopy

Evidence of nanoscale Anderson localization induced by intrinsic compositional disorder in InGaN/GaN quantum wells by scanning tunneling luminescence spectroscopy

Multimode scanning near-field photoluminescence spectroscopy and its application for studies of InGaN epitaxial layers and quantum wells

Potential Barrier Formed Around Dislocations in InGaN Quantum Well Structures by Spot Cathodoluminescence Measurements

Contact Info

Product

Resources

About