Nonpolar AlGaN-Cladding-Free Blue Laser Diodes with InGaN Waveguiding (original) (raw)

AlGaN-Free Blue III–Nitride Laser Diodes Grown on c -Plane GaN Substrates

Applied Physics Express, 2010

We report on the fabrication of InGaN-based multiple-quantum-well laser diodes (LDs) emitting at 420 nm. Structures with standard claddings (pand n-AlGaN), asymmetric claddings (p-GaN and n-AlGaN), and AlGaN-free claddings were grown by metal organic vapor phase epitaxy on polar c-plane free-standing GaN substrates. Electrical and optical properties of each LD are presented. Thanks to an optimized design of the InGaN waveguide and active region, cw lasing of a completely AlGaN-free laser diode is demonstrated, with a threshold current density < 5 kA/cm 2 and a differential efficiency per facet of $0:4 W/A without high-reflection coatings.

Indium-tin-oxide clad blue and true green semipolar InGaN/GaN laser diodes

Applied Physics Letters, 2013

Replacing a portion of the upper III-nitride cladding with indium-tin-oxide (ITO) has several potential advantages for GaN-based laser diodes (LDs). For green LDs, use of ITO in the waveguide structure reduces the epitaxial p-cladding thickness and growth time, which in turn may reduce thermal damage to the active region. We design ITO-clad blue and green semipolar ð20 21Þ LDs using asymmetric InGaN waveguiding layers to center the mode on the active region. Lasing is demonstrated at 471 nm with threshold current density of 6.2 kA/cm 2 for a device with 200 nm p-GaN and at 518 nm for a device with only 300 nm of p-GaN. V C 2013 AIP Publishing LLC.

Properties of InGaN blue laser diodes grown on bulk GaN substrates

Journal of Crystal Growth, 2005

High-pressure growth from solution is at present the only method able to provide true bulk GaN monocrystals. In this paper, we would like to demonstrate that in spite of their small, centimeter range size, they can become a technological platform for the realization of high-quality violet and near-UV laser diodes. We used MOVPE technique to deposit InGaN/AlGaN/GaN layers forming a separate confinement heterostructure laser diode. These devices are characterized by a low density of dislocations ($10 5 cm À2 ) and a high optical output power of 1.9 W, measured in short pulses (30 ns) to prevent the structure from overheating. We will briefly discuss the challenges we face during the process of optimization of these devices. r

High Quality InGaN/AlGaN Multiple Quantum Wells for Semipolar InGaN Green Laser Diodes

The growth of InGaN/AlGaN multiple quantum wells (MQWs) structures is highly effective for realizing high quality semipolar (20 21) active regions for green light emitting diodes (LEDs) and laser diodes (LDs). The use of AlGaN barriers significantly improved internal quantum efficiencies and the uniformity of the emission compared to InGaN or GaN barriers. 516 nm lasing wavelength was demonstrated on semipolar (20 21) GaN substrates by introducing three periods InGaN/AlGaN MQWs and the AlGaN-cladding-free optical waveguide consisting of GaN cladding and InGaN guiding layers. #

AlGaN-Cladding Free Green Semipolar GaN Based Laser Diode with a Lasing Wavelength of 506.4 nm

We demonstrate electrically driven InGaN based laser diodes (LDs), with a simple AlGaN-cladding-free epitaxial structure, grown on semipolar ð20 " 21Þ GaN substrates. The devices employed In 0:06 Ga 0:94 N waveguiding layers to provide transverse optical mode confinement. A maximum lasing wavelength of 506.4 nm was observed under pulsed operation, which is the longest reported for AlGaN-cladding-free III-nitride LDs. The threshold current density (J th ) for index-guided LDs with uncoated etched facets was 23 kA/cm 2 , and 19 kA/cm 2 after application of highreflectivity (HR) coatings. A characteristic temperature (T 0 ) value of 130Kandwavelengthred−shiftof130 K and wavelength red-shift of 130Kandwavelengthred−shiftof0:05 nm/K were confirmed.

Blue-Green InGaN/GaN Laser Diodes on Miscut m -Plane GaN Substrate

Applied Physics Express, 2009

Nonpolar blue-green (481 nm) InGaN/GaN laser diodes (LDs) were realized by using m-plane GaN substrates with a misorientation angle of approximately 1 toward [000 1] direction. The laser diode structures grown on miscut m-plane GaN substrates showed significantly smoother surface morphology compared to structures grown on nominally on-axis m-plane GaN substrates. It is contributed to lower threshold current densities, longer lasing wavelength, and higher lasing yield than those on on-axis substrates grown by the same growth condition. Material improvement based on the control of substrate misorientation is essential to achieve high performance LDs beyond the blue spectral range. #

Blue-Green InGaN/GaN Laser Diodes on Miscut m-Plane GaN Substrate T

AlGaN-Cladding-Free mmm-Plane InGaN/GaN Laser Diodes with p-Type AlGaN Etch Stop Layers

Applied Physics Express, 2011

We present a new method of improving the accuracy and reproducibility of dry etching processes for ridge waveguide InGaN/GaN laser diodes (LDs). A GaN:Al 0:09 Ga 0:91 N etch rate selectivity of 11 : 1 was demonstrated for an m-plane LD with a 40 nm pAl 0:09 Ga 0:91 N etch stop layer (ESL) surrounded by Al-free cladding layers, establishing the effectiveness of AlGaN-based ESLs for controlling etch depth in ridge waveguide InGaN/ GaN LDs. These results demonstrate the potential for integrating AlGaN ESLs into commercial device designs where accurate control of the etch depth of the ridge waveguide is necessary for stable, kink-free operation at high output powers.

True green semipolar InGaN-based laser diodes beyond critical thickness limits using limited area epitaxy

Journal of Applied Physics, 2013

Semipolar oriented laser diodes (LDs) have fundamental advantages over c-plane oriented LDs, however, the thickness and composition of InGaN waveguiding layers and AlGaN cladding are limited by the onset of stress relaxation via threading dislocation glide on the c-plane slip system. Limited area epitaxy minimizes misfit dislocation (MD) formation by preventing pre-existing TDs from entering a patterned mesa. We examine the effects of mesa height and facet evolution for LAE grown strained layers. Significant MD formation was suppressed by at least a factor of four for Al 0.1 Ga 0.9 N/GaN superlattices, enabling AlGaN-clad structures similar to those used in c-plane LDs. We then demonstrate AlGaN-clad blue (456 nm) LDs with threshold current density (J th) of 4.5 kA/cm 2 and GaN-clad true green (523 nm) LDs with J th of 12 kA/cm 2. TEM measurements of the green LD confirm reduction of MD densities with reduction of MD run length. LAE is effective for improving the optical confinement factor of semipolar LDs and offers a glimpse of the design space that may soon be available using low TD density bulk GaN substrates. V

High-Performance Blue InGaN Laser Diodes With Single-Quantum-Well Active Layers

IEEE Photonics Technology Letters, 2007

The authors report on the high-performance blue laser diodes (LDs) with an emission wavelength of 448 nm employing InGaN single-quantum-well (QW) active layers. At 100-mW continuous-wave (CW) output power, operation current and voltage are, respectively, 150 mA and 5.3 V, corresponding to the wall plug efficiency of >12%, a record value for the single-mode InGaN LDs with blue wavelengths. The single QW blue LD showed normal temperature dependence of light output-current curves with the characteristic temperature of 170 K. In addition, we demonstrate a high level of catastrophic optical damage of >300 mW and long device lifetime under CW operation condition at room temperature.

Nonpolar AlGaN-Cladding-Free Blue Laser Diodes with InGaN Waveguiding (original) (raw)

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