Group III nitride-based green-laser diodes and waveguide structures thereof

A Group III nitride-based laser diode comprising an n-side cladding layer formed of n-doped (Al,In)GaN, an n-side waveguide layer formed of n-doped (Al)InGaN, an active region, a p-side waveguide layer formed of p-doped (Al)InGaN, and a p-side cladding layer formed ofp-doped (Al,In)GaN, wherein:

• the active region is interposed between the n-side cladding layer and the p-side cladding layer and extends substantially parallel to the n-side cladding layer and the p-side cladding layer;
• the active region comprises one or more InGaN quantum wells producing electrically-pumped stimulated emission of photons and having optical gain at a lasing wavelength from 510 nm to 580 nm;
• the n-side waveguide layer is interposed between the active region and the n-side cladding layer;
• the n-side waveguide layer has an n-side waveguide layer thickness from 125 nm to 200 nm;
• the p-side waveguide layer is interposed between the active region and the p-side cladding layer;
• the p-side waveguide layer has a p-side waveguide layer acceptor concentration less than 3 ×1017 cm−3 and a p-side waveguide layer thickness from 1 nm to 20% of the n-side waveguide layer thickness;
• the p-side cladding layer has a p-side cladding layer total thickness of from about 0.5 μm to about 1.5μm;
• the p-side cladding layer comprises a first thickness portion and a second thickness portion, the first thickness portion being interposed between the second thickness portion and the p-side waveguide layer;
• the first thickness portion of the p-side cladding layer has a first-portion thickness of 20 nm to 200 nm and a first-portion acceptor concentration less than 3×1017 cm−3;
• and
• the second thickness portion of the p-side cladding layer has a second-portion acceptor concentration greater than 3 ×1017 cm−3;
• the p-side cladding layer has a compositional gradient of aluminum;
• a first aluminum concentration of from 0% to 5% defines a first zone of the p-side cladding layer;
• a second aluminum concentration of from 5% to 20% defines a second zone of the p-side cladding layer;
• aluminum concentration increases through the thickness of the p-side cladding layer with increasing distance from the p-side waveguide layer;
• the first zone extends from an interface of the p-side cladding layer with the p-side waveguide layer and has a thickness of about 20 nm to about 200 nm;
• and
• the second zone is disposed immediately adjacent the first zone opposite the p-side waveguide layer.

A Group III nitride-based laser diode comprising an n-side cladding layer formed of n-doped (Al,In)GaN, an n-side waveguide layer formed of n-doped (Al)InGaN, an active region, a p-side waveguide layer formed of p-doped (Al)InGaN, and a p-side cladding layer formed of p-doped (Al,In)GaN, wherein:

• the active region is interposed between the n-side cladding layer and the p-side cladding layer and extends substantially parallel to the n-side cladding layer and the p-side cladding layer;
• the active region comprises one or more InGaN quantum wells producing electrically-pumped stimulated emission of photons and having optical gain at a lasing wavelength from 510 nm to 580 nm;
• the n-side waveguide layer is interposed between the active region and the n-side cladding layer;
• the n-side waveguide layer has an n-side waveguide layer indium concentration from about 3% to about 11%;
• the p-side waveguide layer is interposed between the active region and the p-side cladding layer;
• the p-side waveguide layer has a p-side waveguide layer acceptor concentration less than 3 ×1017 cm−3 and a p-side waveguide layer indium concentration from about 0% to about 9%;
• the p-side waveguide layer has a p-side waveguide layer thickness of from 1 nm to 20% of an n-side waveguide layer thickness of the n-side waveguide layer;
• the p-side waveguide layer indium concentration is less than the n-side waveguide layer indium concentration;
• the p-side waveguide layer, the n-side waveguide layer, or both, are compositionally graded (Al)InGaN layers each having a gradient indium concentration;
• each gradient indium composition defines an indium-rich zone adjacent to the active region in the respective waveguide layer;
• each indium-rich zone has a thickness of from 0.1% to 75% of the respective waveguide layer thickness;
• the indium-rich zone has an average indium concentration from 5% to 50%;
• the remainder of the respective waveguide layer outside the indium-rich zone has an average indium concentration of from 0% to 10%;
• the average indium concentration of the indium-rich zone is higher than the average indium concentration of the remainder of the respective waveguide;
• and
• the indium concentration difference of the indium-rich zone and the remainder of the respective waveguide is at least 3%;
• the p-side cladding layer has a p-side cladding layer total thickness of from about 0.5 μm to about 1.5 μm;
• the p-side cladding layer comprises a first thickness portion and a second thickness portion, the first thickness portion being interposed between the second thickness portion and the p-side waveguide layer;
• the first thickness portion of the p-side cladding layer has a first-portion thickness of 20 nm to 200 nm and a first-portion acceptor concentration less than 3 ×1017 cm −3;
• and
• the second thickness portion of the p-side cladding layer has a second-portion acceptor concentration greater than 3 ×1017 cm −3.