450 nm GaInN ridge stripe laser diodes with AlInN/AlGaN multiple cladding layers

Abstract

We investigated and improved optical waveguides along the vertical and horizontal directions in 450 nm GaInN laser diodes. As a result, we demonstrated a low threshold current density (1.15 kA cm−2) of a GaInN ridge stripe laser diode containing a 3-pair 40 nm Al0.82In0.18N/25 nm Al0.03Ga0.97N multiple bottom cladding layer at room temperature under pulsed condition. This threshold current density is smaller than our typical value with a 1 μm Al0.03Ga0.97N bottom cladding layer. AlInN/AlGaN multiple layers are useful as n-type cladding layers in visible laser diodes to achieve higher optical confinement factors while smooth surfaces were obtained.

Analysis of Spontaneous Subpeak Emission from the Guide Layers of the Ultraviolet‐B Laser Diode Structure Containing Composition‐Graded p‐AlGaN Cladding Layers

“…[21,22] Meanwhile, guide emission was not dominant in several cases of the GaInN-based visible LD or AlGaN-based UVA LD. [23][24][25][26][27][28][29][30] Subsequently, a comparison between AlGaN-and GaInN-based LDs was sought via simulation with the base structure of a blue-violet LD following the reported structure. [31] The simulation was simplified by modifying the p-AlGaN superlattice design to a bulk p-GaN layer.…”

Metalorganic Chemical Vapor Deposition of over 150‐nm‐Thick Quaternary AlGaInN Epitaxial Films near Alloy Composition Lattice‐Matching to GaN on Sapphire and Their Structural and Optical Characterization

“…GaN/AlGaN superlattices or single‐layer AlGaN films have often been used as cladding layers in GaN‐based visible LDs because their refractive index can be lowered by increasing their AlN molar fraction. AlInN alloys are also viewed as a candidate for cladding layers in GaN LDs . This is because AlInN shows very large index contrasts to GaN or GaInN in whole visible wavelengths at alloy compositions nearly lattice‐matching to c ‐plane GaN .…”

Low-threshold-current (~85 mA) of AlGaN-based UV-B laser diode with refractive-index waveguide structure

“…Therefore, one possible mean to reduce the I th and the V th is believed that the device employs a refractive-index guide structure such as a ridge waveguide structure, which enables to increase the light confinement in the lateral direction. [25][26][27][28] That is, when this structure is employed in the device, the J th is not expected to increase significantly in in spite of the narrowed p-type electrode. Notably, AlGaN-based materials typically do not allow uniform current injection to the active layer due to the high resistance of the p-type cladding layer.…”