A semiconductor laser diode type of a buried-hetero structure (BH-LD) is disclosed. The LD provides a mesa, a first burying layer, and a second burying layer, where the burying layers are provided in respective sides of the mesa so as to expose a top of the mesa. The mesa includes a lower cladding layer, an active layer, and an upper cladding layer, where the cladding layers have conduction type opposite to each other and, combined with the burying layers, constitute a carrier confinement structure. The second burying layer has an even surface overlapping with an even surface of the first burying layer, and has a thickness in a portion of the even surface that is thinner than a thickness thereof in a portion except for the even surface.

To improve characteristics of a semiconductor device (semiconductor laser), an active layer waveguide (AWG) comprised of InP is formed over an exposed part of a surface of a substrate having an off angle ranging from 0.5 to 1.0 in a [1-1-1] direction from a (100) plane to extend in the [0-1-1] direction. A cover layer comprised of p-type InP is formed over the AWG with a V/III ratio of 2000 or more. Thereby, it is possible to obtain excellent multiple quantum wells (MQWs) by reducing a film thickness variation of the AWG. Moreover, the cover layer having side faces where a (0-11) plane almost perpendicular to a substrate surface mainly appears can be formed. A sectional shape of a lamination part of the cover layer and the AWG becomes an approximately rectangular shape. Therefore, an electrification region can be enlarged and it is possible to reduce a resistance of the semiconductor device.

The subject matter disclosed herein relates to formation of silicon germanium devices with tensile strain. Tensile strain applied to a silicon germanium device in fabrication may improve performance of a silicon germanium laser or light detector.

A quantum cascade laser includes a substrate having first and second substrate regions arranged along a first axis; a laser structure body including a laser body region having laser waveguide structures extending along the first axis, the laser structure body including first and second regions respectively including the first and second substrate regions, the laser body region having an end facet located at a boundary between the first and second regions, the second region including a terrace extending along the first axis from a bottom edge of the end facet; a plurality of first electrodes disposed on the laser waveguide structures; a plurality of pad electrodes disposed on the terrace; and a plurality of wiring metal bodies each of which includes a first portion on the terrace and a second portion on the end facet. The pad electrodes are connected with the first electrodes through the wiring metal bodies, respectively.

A semiconductor device according to the present disclosure includes a main part that includes a semiconductor substrate, a first cladding layer provided on the semiconductor substrate, an active layer provided on the first cladding layer, and a second cladding layer provided on the active layer, and in which a flat part and a mesa part are formed, the mesa part including the active layer and a first embedded layer covering a top surface of the flat part and a side surface of the mesa part, wherein the first embedded layer has a projecting part on a top surface of a portion provided in a region within a height of the mesa part from a boundary between the mesa part and the flat part in the top surface of the flat part.