Photonic devices such as semiconductor lasers and photodetectors of various operating wavelengths are grown monolithically on a Silicon substrate, and formed of nanowire structures with quantum structures as active regions. A reduction of strain during fabrication results from the use of these nanowire structures, thereby allowing devices to operate for extended periods of time at elevated temperatures. Monolithic photonic devices and monolithic photonic integrated circuits formed on Silicon substrates are thus provided.

Embodiments of the present disclosure are directed towards a laser device with a stepped graded index separate confinement heterostructure (SCH), in accordance with some embodiments. One embodiment includes a substrate area, and an active region adjacent to the substrate area. The active region includes an SCH layer, which comprises a first portion and a second portion adjacent to the first portion. A composition of the first portion is graded to provide a first conduction band energy increase over a distance from multiple quantum wells (MQW) to a p-side of a laser device junction. A composition of the second portion is graded to provide a second conduction band energy increase over the MQW to the p-side distance. The first conduction band energy increase is different than the second conduction band energy increase. Other embodiments may be described and/or claimed.

Photonic devices such as semiconductor lasers and photodetectors of various operating wavelengths are grown monolithically on a Silicon substrate, and formed of nanowire structures with quantum structures as active regions. A reduction of strain during fabrication results from the use of these nanowire structures, thereby allowing devices to operate for extended periods of time at elevated temperatures. Monolithic photonic devices and monolithic photonic integrated circuits formed on Silicon substrates are thus provided.

The invention relates to an AlInGaN alloy based laser diode, which uses a gallium nitride substrate. It also includes a lower cladding layer, a lower light-guiding layer-cladding, a light emitting layer, an upper light-guiding-cladding layer, an upper cladding layer, and a subcontact layer. The lower light-guiding-cladding layer and the upper light-guiding-cladding layer have a continuous, non-step-like and smooth change of indium and/or aluminium content.

A semiconductor laser element includes an n-side semiconductor layer, an active layer, and a p-side semiconductor layer, layered upward in this order, each being made of a nitride semiconductor. The active layer includes one or more well layers, and an n-side barrier layer located lower than the one or more well layers. The n-side semiconductor layer includes a composition-graded layer located in contact with the n-side barrier layer. The composition-graded layer has a band-gap energy that decreases toward an upper side of the composition-graded layer, with a band-gap energy of the upper side being smaller than a band-gap energy of the n-side barrier layer. The composition-graded layer has an n-type dopant concentration greater than 510.sup.17/cm.sup.3 and less than or equal to 210.sup.18/cm.sup.3. The n-side barrier layer has an n-type dopant concentration greater than that of the composition-graded layer and a thickness smaller than that of the composition graded layer.

A semiconductor laser element includes an n-side semiconductor layer, an active layer, and a p-side semiconductor layer, layered upward in this order, each being made of a nitride semiconductor. The active layer includes one or more well layers, and an n-side barrier layer located lower than the one or more well layers. The n-side semiconductor layer includes a composition-graded layer located in contact with the n-side barrier layer. The composition-graded layer has a band-gap energy that decreases toward an upper side of the composition-graded layer, with a band-gap energy of the upper side being smaller than a band-gap energy of the n-side barrier layer. The composition-graded layer has an n-type dopant concentration greater than 510.sup.17/cm.sup.3 and less than or equal to 210.sup.18/cm.sup.3. The n-side barrier layer has an n-type dopant concentration greater than that of the composition-graded layer and a thickness smaller than that of the composition graded layer.

A semiconductor laser comprises: a substrate; a first cladding layer disposed above the substrate; a second cladding layer disposed above the first cladding layer so that the first cladding layer is positioned between the substrate and the second cladding layer; and a first mode expansion layer within the first cladding layer, a second mode expansion layer within the second cladding layer, or both the first mode expansion layer within the first cladding layer and the second mode expansion layer within the second cladding.

In some implementations, a method may include forming a quantum well (QW) layer using an epitaxial growth process, where the epitaxial growth process is performed according to a first growth mode to form the QW layer. The method may include forming a quantum well barrier (QWB) layer using the epitaxial growth process, where the epitaxial growth process is performed according to a second growth mode to form the QWB layer. In some implementations, a nitrogen flux used in the first growth mode is different from a nitrogen flux used in the second growth mode. In some implementations, a gallium flux used in the first growth mode is different from a gallium flux used in the second growth mode.