Daniel Feezell - Academia.edu (original) (raw)

Papers by Daniel Feezell

Electrically-injected GaN-based vertical-cavity surface-emitting lasers (VCSELs) are of considera... more Electrically-injected GaN-based vertical-cavity surface-emitting lasers (VCSELs) are of considerable interest for data storage, printing, solid-state lighting, and displays. However, these devices face significant technological challenges, such as realizing an ohmic intra-cavity contact and an effective lateral current-distribution scheme. We report a promising current-injection scheme for GaN-based VCSELs consisting of a patterned Si3N4 current aperture and a thin Pd/Au intra-cavity contact and lateral current-distribution layer. We examine the optical loss introduced by the thin metal layer and discuss a loss minimization method. A finite element electrical model is then used to predict the lateral current-distribution benefits. Finally, we fabricate and characterize LEDs utilizing this current-injection scheme. These devices operate at direct-current (DC) current densities exceeding 10kA/cm^2, exhibit ohmic contacts, and demonstrate effective lateral current distribution across aperture diameters up to 36μm.

Proceedings of Spie the International Society For Optical Engineering, Apr 1, 2010

We present state-of-the-art performance from green, blue, and violet InGaN-based laser diodes fab... more We present state-of-the-art performance from green, blue, and violet InGaN-based laser diodes fabricated on nonpolar and semipolar GaN substrates. Using these novel crystal orientations, we demonstrate high power, high efficiency, continuous-wave operation from single-lateral-mode electrically pumped laser diodes at wavelengths from 405 nm to 500 nm. Additionally, we present the longest reported continuous-wave lasing demonstration of 525 nm and an output power of over 9 mW at 521 nm. Wall-plug efficiencies of over 25% in the violet region, 17.5% in the blue region, over 5% at 472nm, and 2.2% in the 500 nm range are reported. These InGaN-based devices offer dramatic improvement in size, weight, and cost over conventional gas and solid state lasers and may enable a variety of new applications in defense and security.

Appl Phys Express, 2011

We report a high-power blue light-emitting diode (LED) with a high external quantum efficiency an... more We report a high-power blue light-emitting diode (LED) with a high external quantum efficiency and low droop on a free-standing (2021) GaN substrate. At a forward current of 20 mA, the LED showed a peak external quantum efficiency of 52% and an output power of 30.6 mW. In higher current density regions, the LED also showed outstanding performance, with droop ratios of 0.7% at 35 A/cm2, 4.3% at 50 A/cm2, 8.5% at 100 A/cm2, and 14.3% at 200 A/cm2. The output power and external quantum efficiency at 200 A/cm2 were 266.5 mW and 45.3%, respectively.

Proceedings of Spie the International Society For Optical Engineering, Feb 1, 2010

We present new advances in green, blue, and violet InGaN-based laser diodes fabricated on nonpola... more We present new advances in green, blue, and violet InGaN-based laser diodes fabricated on nonpolar and semipolar GaN substrates. Using these novel crystal orientations, we report high power, high efficiency, continuous-wave operation from single-lateral-mode electrically pumped laser diodes at wavelengths from 405 nm to 500 nm. Additionally, we present continuous-wave lasing demonstrations out to 523 nm, representing the longest continuous-wave green laser emission reported to date. Wall-plug efficiencies of over 25% in the violet region, 16.2% in the blue region, and 2.2% in the 500 nm range are presented. These InGaN-based devices offer dramatic improvement in size, weight, and cost over conventional gas or solid state lasers and may enable a variety of new applications in defense, biomedical, industrial, and consumer projection displays.

Japanese Journal of Applied Physics, Mar 30, 2007

We demonstrate highly manufacturable nonpolar (m-plane) InGaN/GaN laser diodes without any Al-con... more We demonstrate highly manufacturable nonpolar (m-plane) InGaN/GaN laser diodes without any Al-containing waveguide cladding layers. These devices utilize thick InGaN quantum wells to generate transverse optical mode confinement and can be grown and fabricated in a manner analogous to InGaN/GaN light emitting diodes. Pulsed lasing operation was demonstrated, with threshold voltages and current densities of 6.7 V and 3.7 kA/cm2, respectively.

$Research paper thumbnail of Semipolar <formula formulatype="inline"><tex Notation="TeX">$({\hbox{20}}\bar{{\hbox{2}}}\bar{{\hbox{1}}})$</tex> </formula> InGaN/GaN Light-Emitting Diodes for High-Efficiency Solid-State Lighting$

Journal of Display Technology, 2013

ABSTRACT This work examines the effects of polarization-related electric fields on the energy ban... more ABSTRACT This work examines the effects of polarization-related electric fields on the energy band diagrams, wavelength shift, wave function overlap, and efficiency droop for InGaN quantum wells on various crystal orientations, including polar (0001) (c-plane), semipolar (20 (2) over bar1), semipolar (20 (2) over bar(1) over bar), and non-polar (10 (1) over bar0) (m-plane). Based on simulations, we show that the semipolar (20 (2) over bar(1) over bar) orientation exhibits excellent potential for the development of high-efficiency, low-droop light-emitting diodes (LEDs). We then present recent advancements in crystal growth, optical performance, and thermal performance of semipolar (20 (2) over bar(1) over bar) LEDs. Finally, we demonstrate a low-droop, high-efficiency single-quantum-well blue semipolar (20 (2) over bar(1) over bar) LED with an external quantum efficiency of more than 50% at 100 A/cm(2).

GaN-based semipolar (20 (21) over bar) laser diodes (lambda=505 nm) with a 4 nm wavelength bluesh... more GaN-based semipolar (20 (21) over bar) laser diodes (lambda=505 nm) with a 4 nm wavelength blueshift from spontaneous emission to lasing are demonstrated. The minimal blueshift is attributed to the stable energy profile in the quantum wells.

Conference on Lasers and Electro-Optics 2012, 2012

ABSTRACT Growth on relaxed buffers provides a potential route to reduce difficulties caused by hi... more ABSTRACT Growth on relaxed buffers provides a potential route to reduce difficulties caused by high strain (∼ 3%) in the In0.3Ga0.7N active regions of green laser diodes (LDs). We demonstrate a blue LD with partially relaxed n- and p-side waveguide/cladding interfaces.

Applied Physics Letters, 2014

63rd Device Research Conference Digest, 2005. DRC '05., 2005

In this paper, the authors designed a 1.3mum VCSEL with Sb-based DBR technology and demonstrated ... more In this paper, the authors designed a 1.3mum VCSEL with Sb-based DBR technology and demonstrated its first CW operation. It has achieved record-high CW differential efficiencies. High speed modulation was also demonstrated for the first time with this technology. Coupled with previous results at 1.55mum, these results clearly demonstrate this platform's ability to generate high-performance monolithic VCSELs spanning the entire 1.3-1.6mum wavelength window

2007 IEEE Compound Semiconductor Integrated Circuits Symposium, 2007

ABSTRACT This article discusses recent advances of nonpolar and semipolar GaN-based light emittin... more ABSTRACT This article discusses recent advances of nonpolar and semipolar GaN-based light emitting diodes (LEDs) and laser diodes (LDs). Devices fabricated on these alternative orientations are already beginning to realize significant performance milestones. Nonpolar GaN has been employed to facilitate high-power LEDs and to realize CW operation of novel AlGaN-cladding-free LD structures. Semipolar GaN has also been successfully used to demonstrate LDs and to realize high-power, high-efficiency green LEDs.

Semiconductor Lasers, 2013

Materials Today, 2011

GaN based laser diodes (LDs) have entered widespread use as the laser source for high-density opt... more GaN based laser diodes (LDs) have entered widespread use as the laser source for high-density optical data storage (e.g., Blu-ray discs), as well as new applications in laser based projectors and TVs. Data density for optical storage technology is limited by the wavelength of the light source used to read and write data, with shorter wavelengths leading to higher data density. GaN along with InN and AlN form the only short wavelength direct bandgap materials system that has shown both p-and n-type doping and sufficiently long device lifetime for successful commercialization.

Journal of Display Technology

This work examines the effects of polarization-related electric fields on the energy band diagram... more This work examines the effects of polarization-related electric fields on the energy band diagrams, wavelength shift, wave function overlap, and efficiency droop for InGaN quantum wells on various crystal orientations, including polar (0001) (c-plane), semipolar (20-21), semipolar (20-2-1, and nonpolar (10-10) (m-plane). Based on simulations, we show that the semipolar (20-2-1) orientation exhibits excellent potential for the development of high-efficiency, low-droop light-emitting diodes (LEDs). We then present recent advancements in crystal growth, optical performance, and thermal performance of semipolar (20-2-1) LEDs. Finally, we demonstrate a low-droop, high-efficiency single-quantum-well blue semipolar (20-2-1) LED with an external quantum efficiency of more than 50% at 100 A/cm2.

Optics express, Jan 14, 2013

Linear polarized electroluminescence was investigated for semipolar (3031) and (3031) InGaN light... more Linear polarized electroluminescence was investigated for semipolar (3031) and (3031) InGaN light-emitting diodes (LEDs) with various indium compositions. A high degree of optical polarization was observed for devices on both planes, ranging from 0.37 at 438 nm to 0.79 at 519 nm. The extracted valence band energy separation was consistent with the optical polarization ratios. The effect of anisotropic strain on the valance band structure was studied using k?p method for the above two planes. The theoretical calculations are consistent with the experimental results.