Reduction of dislocation density in Al0.6Ga0.4N film grown on sapphire substrates using annealed sputtered AlN templates and its effect on UV-B laser diodes

ABSTRACTIn order to reduce vertical leakage in III-nitride detectors, we have grown a patterned array of hexagonal GaN columns on masked heteroepitaxial GaN template layers using a-plane sapphire substrates. In addition to eliminating cracking, we have found that for GaN columns tens of microns in diameter and several microns high, the dislocation density is also significantly reduced. We have developed a simple closed-form analytical model for predicting the critical column height for the onset of the reduction in the dislocation density. Among the predictions of this model is that the critical column height for the onset of dislocation density reduction is proportional to the product of column width and the grain size of the GaN film.

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Semipolar {202̅1} GaN Edge-Emitting Laser Diode on Epitaxial Lateral Overgrown Wing

Crystals ◽

10.3390/cryst11121563 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1563

Author(s):

Srinivas Gandrothula ◽

Haojun Zhang ◽

Pavel Shapturenka ◽

Ryan Anderson ◽

Matthew S. Wong ◽

...

Keyword(s):

Dislocation Density ◽

Output Power ◽

Laser Diode ◽

Laser Diodes ◽

Light Output ◽

Laser Action ◽

Feasibility Studies ◽

Threshold Current ◽

Optical Measurements ◽

Light Output Power

Edge-emitting laser diodes (LDs) were fabricated on a reduced dislocation density epitaxial lateral overgrown (ELO) wing of a semipolar {202̅1} GaN substrate, termed an ELO wing LD. Two types of facet feasibility studies were conducted: (1) “handmade” facets, wherein lifted-off ELO wing LDs were cleaved manually, and (2) facets formed on wafers through reactive ion etching (RIE). Pulsed operation electrical and optical measurements confirmed the laser action in the RIE facet LDs with a threshold current of ~19 kAcm−2 and maximum light output power of 20 mW from a single uncoated facet. Handmade facet devices showed spontaneous, LED-like emission, confirming device layers remain intact after mechanical liftoff.

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Demonstration of Efficient Semipolar 410 nm Violet Laser Diodes Heteroepitaxially Grown on High-Quality Low-Cost GaN/Sapphire Substrates

ACS Applied Electronic Materials ◽

10.1021/acsaelm.0c00364 ◽

2020 ◽

Vol 2 (7) ◽

pp. 1874-1879

Author(s):

Hongjian Li ◽

Panpan Li ◽

Haojun Zhang ◽

Shuji Nakamura ◽

Steven P. DenBaars

Keyword(s):

Low Cost ◽

Laser Diodes ◽

High Quality ◽

Sapphire Substrates

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Low dislocation density, high power InGaN laser diodes

MRS Internet Journal of Nitride Semiconductor Research ◽

10.1557/s1092578300000387 ◽

2004 ◽

Vol 9 ◽

Cited By ~ 8

Author(s):

Piotr Perlin ◽

M. Leszczyñski ◽

P. Prystawko ◽

P. Wisniewski ◽

R. Czernetzki ◽

...

Keyword(s):

Dislocation Density ◽

High Power ◽

Laser Diodes ◽

Epitaxial Lateral Overgrowth ◽

Homogeneous Distribution ◽

Lateral Overgrowth ◽

Low Dislocation Density ◽

Bulk Gan ◽

New Generation ◽

Better Than

We used single crystals of GaN, obtained from high-pressure synthesis, as substrates for Metalorganics Vapor Phase Epitaxy growth of violet and UV laser diodes. The use of high-quality bulk GaN leads to the decrease of the dislocation density to the low level of 105 cm−2, i.e. two orders of magnitude better than typical for the Epitaxial Lateral Overgrowth laser structures fabricated on sapphire. The low density and homogeneous distribution of defects in our structures enables the realization of broad stripe laser diodes. We demonstrate that our laser diodes, having 15 μm wide stripes, are able to emit 1.3-1.9 W per facet (50% reflectivity) in 30 ns long pulses. This result, which is among the best ever reported for nitride lasers, opens the path for the development of a new generation of high power laser diodes.

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