scholarly journals Pursuing the Diffraction Limit with Nano-LED Scanning Transmission Optical Microscopy

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3305
Author(s):  
Sergio Moreno ◽  
Joan Canals ◽  
Victor Moro ◽  
Nil Franch ◽  
Anna Vilà ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Light Emitting Diode ◽  
Optical Resolution ◽  
Diffraction Limit ◽  
Resolution Limit ◽  
Light Emitting ◽  
Gan Led ◽  
Scanning Transmission ◽  
On Chip ◽  
Microscopy Techniques

Recent research into miniaturized illumination sources has prompted the development of alternative microscopy techniques. Although they are still being explored, emerging nano-light-emitting-diode (nano-LED) technologies show promise in approaching the optical resolution limit in a more feasible manner. This work presents the exploration of their capabilities with two different prototypes. In the first version, a resolution of less than 1 µm was shown thanks to a prototype based on an optically downscaled LED using an LED scanning transmission optical microscopy (STOM) technique. This research demonstrates how this technique can be used to improve STOM images by oversampling the acquisition. The second STOM-based microscope was fabricated with a 200 nm GaN LED. This demonstrates the possibilities for the miniaturization of on-chip-based microscopes.

On-chip cavity-enhanced absorption spectroscopy using a white light-emitting diode and polymer mirrors

Lab on a Chip ◽  
2015 ◽  
Vol 15 (3) ◽  
pp. 711-717 ◽  
Author(s):  
Cathy M. Rushworth ◽  
Gareth Jones ◽  
Martin Fischlechner ◽  
Emma Walton ◽  
Hywel Morgan
Keyword(s):  
Absorption Spectroscopy ◽  
White Light ◽  
Microfluidic Chip ◽  
Path Length ◽  
Light Emitting Diode ◽  
Absorption Path Length ◽  
Light Emitting ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
On Chip

We have integrated disposable polymer mirrors within a microfluidic chip to form a multi-pass cell, which increases the absorption path length by a maximum of 28 times, providing micromolar detection limits in a probed volume of 10 nL.

N-face GaN substrate roughening for improved performance GaN-on-GaN LED

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ezzah Azimah Alias ◽  
Muhammad Esmed Alif Samsudin ◽  
Steven DenBaars ◽  
James Speck ◽  
Shuji Nakamura ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Light Emitting Diode ◽  
Optical Power ◽  
Ammonium Hydroxide ◽  
Content Type ◽  
Light Emitting ◽  
Gan Led ◽  
Improved Performance ◽  
Substrate Roughening

Purpose This study aims to focus on roughening N-face (backside) GaN substrate prior to GaN-on-GaN light-emitting diode (LED) growth as an attempt to improve the LED performance. Design/methodology/approach The N-face of GaN substrate was roughened by three different etchants; ammonium hydroxide (NH4OH), a mixture of NH4OH and H2O2 (NH4OH: H2O2) and potassium hydroxide (KOH). Hexagonal pyramids were successfully formed on the surface when the substrate was subjected to the etching in all cases. Findings Under 30 min of etching, the highest density of pyramids was obtained by NH4OH: H2O2 etching, which was 5 × 109 cm–2. The density by KOH and NH4OH etchings was 3.6 × 109 and 5 × 108 cm–2, respectively. At standard operation of current density at 20 A/cm2, the optical power and external quantum efficiency of the LED on the roughened GaN substrate by NH4OH: H2O2 were 12.3 mW and 22%, respectively, which are higher than its counterparts. Originality/value This study demonstrated NH4OH: H2O2 is a new etchant for roughening the N-face GaN substrate. The results showed that such etchant increased the density of the pyramids on the N-face GaN substrate, which subsequently resulted in higher optical power and external quantum efficiency to the LED as compared to KOH and NH4OH.

Electrostatic Discharge Characteristics of InGaN/GaN Light-Emitting Diodes with Si-Doped Graded Superlattice

2015 ◽  
Vol 15 (10) ◽  
pp. 7733-7737 ◽  
Author(s):  
Kwanjae Lee ◽  
Cheul-Ro Lee ◽  
Jin Soo Kim ◽  
Jin Hong Lee ◽  
Kee Young Lim ◽  
...  
Keyword(s):  
Light Emission ◽  
Electrostatic Discharge ◽  
Light Emitting Diode ◽  
Emission Spectra ◽  
Small Variation ◽  
Injection Current ◽  
Light Emitting ◽  
Current Voltage ◽  
Gan Led ◽  
Si Doped

We report the influences of a Si-doped graded superlattice (SiGSL) on the electrostatic discharge (ESD) characteristics of an InGaN/GaN light-emitting diode (LED). For comparison, a conventional InGaN/GaN LED (C-LED) was also investigated. The luminous efficacy for the SiGSL-LED was 2.68 times stronger than that for the C-LED at the injection current of 20 mA. The resistances estimated from current–voltage (I–V) characteristic curves were 16.5 and 8.8 Ω for the C-LED and SiGSL-LED, respectively. After the ESD treatment at the voltages of 4000 and 6000 V, there was no significant change in the I–V curves for the SiGSL-LED. Also, there was small variation in the I–V characteristics for the SiGSL-LED at the ESD voltage of 8000 V. However, the I–V curves for the C-LED were drastically degraded with increasing ESD voltage. While the light emission was not observed at the injection current of 20 mA from the C-LED sample after the ESD treatment, the emission spectra for the SiGSL-LED sample were clearly measured with the output powers of 10.47, 9.66, and 7.27 mW for the ESD voltages of 4000, 6000, and 8000 V respectively.

scholarly journals A Novel Method to Maintain the Sample Position and Pressure in Differentially Pumped Systems Below the Resolution Limit of Optical Microscopy Techniques

2020 ◽  
pp. 000370282094279
Author(s):  
Christopher M. Goodwin ◽  
John D. Alexander ◽  
Matthew Weston ◽  
David Degerman ◽  
Mikhail Shipilin ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Photoelectron Spectroscopy ◽  
Gas Flow ◽  
Feedback System ◽  
Resolution Limit ◽  
X Ray ◽  
System Pressure ◽  
Sample Position ◽  
Microscopy Techniques

We present a new method to maintain constant gas pressure over a sample during in situ measurements. The example shown here is a differentially pumped high-pressure X-ray photoelectron spectroscopy system, but this technique could be applied to many in situ instruments. By using the pressure of the differential stage as a feedback source to change the sample position, a new level of consistency has been achieved. Depending on the absolute value of the sample-to-aperture distance, this technique allows one to maintain the distance within several hundred nanometers, which is below the limit of typical optical microscopy systems. We show that this method is well suited to compensate for thermal drift. Thus, X-ray photoelectron spectroscopy data can be acquired continuously while the sample is heated and maintaining constant pressure over the sample. By implementing a precise manipulator feedback system, pressure variations of less than 5% were reached while the temperature was varied by 400 ℃. The system is also shown to be highly stable under significant changes in gas flow. After changing the flow by a factor of two, the pressure returned to the set value within 60 s.

Spatial Inhomogeneity of Photoluminescence in an InGaN-Based Light-Emitting Diode Structure Probed by Near-Field optical Microscopy Under Illumination-Collection Mode

2001 ◽  
Vol 40 (Part 1, No. 1) ◽  
pp. 110-111 ◽  
Author(s):  
Akio Kaneta ◽  
Tomoaki Izumi ◽  
Koichi Okamoto ◽  
Yoichi Kawakami ◽  
Shigeo Fujita ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Light Emitting Diode ◽  
Near Field ◽  
Diode Structure ◽  
Spatial Inhomogeneity ◽  
Light Emitting

Colloidal quantum dot active layer electroluminescence in a solid GaN matrix

2005 ◽  
Vol 891 ◽  
Author(s):  
Jennifer Pagan ◽  
Edward Stokes ◽  
Kinnari Patel ◽  
Casey Burkhart ◽  
Mike Ahrens
Keyword(s):  
Active Layer ◽  
Light Emitting Diode ◽  
Cdse Quantum Dots ◽  
Light Emitting ◽  
Force Microscopy ◽  
Turn On ◽  
Atomic Force ◽  
Transmission Line Method ◽  
Gan Led ◽  
Colloidal Quantum Dot

ABSTRACTIn this paper the preliminary results of incorporating a novel active layer into a GaN light emitting diode (LED) are discussed. Integration of colloidal CdSe quantum dots into a GaN LED active layer is demonstrated. The conductivity of the overgrowth was examined by circular transmission line method (CTLM). Effects on surface roughness due to the active layer incorporation are examined using atomic force microscopy (AFM). LED test devices were fabricated and electroluminescence was demonstrated, the devices exhibit higher turn-on voltages than would be expected for a CdSe active layer.

scholarly journals Organic optoelectronics for lab-on-chip fluorescence detection

2017 ◽  
Vol 84 (s1) ◽  
Author(s):  
Sabrina Jahns ◽  
Andre F.K. Iwers ◽  
Jan Balke ◽  
Martina Gerken
Keyword(s):  
Fluorescence Detection ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Lab On Chip ◽  
Organic Light Emitting Diode ◽  
Photo Diode ◽  
Organic Optoelectronics ◽  
Organic Light ◽  
On Chip

AbstractWe present two designs of organic optoelectronics for compact lab-on-chip fluorescence detection. In the first configuration, organic light emitting diode (OLED) and organic photo diode (OPD) are fabricated

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