Indium-tin-oxide clad blue and true green semipolar InGaN/GaN laser diodes (original) (raw)
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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.
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
We demonstrate GaN-based semipolar (2021) laser diodes (LD) in the green region of the spectrum. 505 nm lasing was observed under pulsed operation, with a threshold current density (J th ) of 27.5 kA/cm 2 and a threshold voltage (V th ) of 15.5 V. The blueshift of spontaneous emission was less than 5 nm when varying the injection current level from 125 A/cm 2 to threshold. Simulations show that the reduced blueshift can be attributed to the minimal dependence of the energy potential profile in the active region on the applied bias and current injection level.
Blue-Green InGaN/GaN Laser Diodes on Miscut m-Plane GaN Substrate T
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
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. #
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. #
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
Continuous-Wave Operation of InGaN/GaN Laser Diodes on Semipolar (1 1\bar2 2) Plane Gallium Nitrides
Applied Physics Express, 2009
Continuous-wave (CW) operations of semipolar ð11 22Þ plane InGaN/GaN laser diodes (LDs) were demonstrated. The LD structures were grown on low extended defect density semipolar ð11 22Þ GaN bulk substrates, using conventional metal organic chemical vapor deposition (MOCVD) at atmospheric pressure. The threshold current was 54 mA (6.5 kA/cm 2) for the CW operation [39 mA (4.6 kA/cm 2) for pulsed mode]. Stimulated emission was observed at 405.9 nm with a spectral line-width of 1 nm. These results indicate that semipolar ð11 22Þ GaN is a promising orientation for the realization of blue-green and green LDs.
Nonpolar AlGaN-Cladding-Free Blue Laser Diodes with InGaN Waveguiding
Applied Physics Express, 2009
We have demonstrated AlGaN-cladding-free m-plane InGaN-based blue laser diodes (LDs) using a novel structure that employs 50-nmthick n-and p-type In x Ga 1Àx N (x ¼ 5 {10%) as waveguiding layers. The thick, high In content InGaN waveguiding layers provided significant refractive index contrast to the GaN cladding layers, thereby eliminating the need for AlGaN cladding. Under pulsed operation, lasing was achieved at 442 nm with a threshold current density of 10 kA/cm 2 . #
Applied Physics Express, 2008
Semipolar ð11 22Þ plane III-nitride laser diodes (LDs) were realized on low extended defect density semipolar ð11 22Þ GaN bulk substrates. The LD structures were grown by conventional atmospheric-pressure metal organic chemical vapor deposition (MOCVD), using conditions similar to that of c-plane nitride device growth. The mirror facet for a laser cavity was formed by dry-etching of III-V nitride films without cleaving. Stimulated emission was observed at 426.9 nm with a full width at half maximum (FWHM) of less than 1 nm. The ð11 22Þ plane laser diode had threshold currents (I th) of 306 mA, corresponding to a threshold current densities (J th) of 12.8 kA/cm 2 .