A method is presented for forming a germanium (Ge) laser diode with direct bandgap for laser generation. The method includes forming an intrinsic Ge active layer over a substrate, forming a p+ region and an n+ region adjacent the intrinsic Ge active layer, such that the p+ region, the n+ region, and the intrinsic Ge active layer collectively define a p-i-n diode, and forming metal contacts to the p+ and n+ regions.

A structure having first and second layers is disposed on a substrate. The second layer is disposed on the first layer, is compressively strained, and comprises the alloy including germanium and tin. The structure comprises first and second members spaced a distance from each other along a direction, a strip located between the first and second members and extending along an axis intersecting the direction, and arms connecting the first and second members to a first end of the strip. The first and second members, the strip and the arms comprise respective portions of the first and second layers. A portion of the first layer at the strip and arms is removed such that the strip and arms become suspended and the arms remain anchored to the first layer via the first and second members. Tensile strain is induced in the alloy via the arms. The alloy may perform lasing.

A light source comprises a GeSn active zone inserted between two contact zones. The active zone is formed directly on a silicon oxide layer by a first lateral epitaxial growth of a Ge germination layer followed by a second lateral epitaxial growth of a GeSn base layer. A cavity is formed between the contact zones by encapsulation and etching, so as to guide these lateral growths. A vertical growth of GeSn is then achieved from the base layer to form a structural layer. The active zone is formed in the stack of base and structural layers.

Tensile strained germanium is provided that can be sufficiently strained to provide a nearly direct band gap material or a direct band gap material. Compressively stressed or tensile stressed stressor materials in contact with germanium regions induce uniaxial or biaxial tensile strain in the germanium regions. Stressor materials may include silicon nitride or silicon germanium. The resulting strained germanium structure can be used to emit or detect photons including, for example, generating photons within a resonant cavity to provide a laser.

A germanium waveguide is formed from a P-type silicon substrate that is coated with a heavily-doped N-type germanium layer and a first N-type doped silicon layer. Trenches are etched into the silicon substrate to form a stack of a substrate strip, a germanium strip, and a first silicon strip. This structure is then coated with a silicon nitride layer.

Tensile strained germanium is provided that can be sufficiently strained to provide a nearly direct band gap material or a direct band gap material. Compressively stressed or tensile stressed stressor materials in contact with germanium regions induce uniaxial or biaxial tensile strain in the germanium regions. Stressor materials may include silicon nitride or silicon germanium. The resulting strained germanium structure can be used to emit or detect photons including, for example, generating photons within a resonant cavity to provide a laser.

A light source comprises a GeSn active zone inserted between two contact zones. The active zone is formed directly on a silicon oxide layer by a first lateral epitaxial growth of a Ge germination layer followed by a second lateral epitaxial growth of a GeSn base layer. A cavity is formed between the contact zones by encapsulation and etching, so as to guide these lateral growths. A vertical growth of GeSn is then achieved from the base layer to form a structural layer. The active zone is formed in the stack of base and structural layers.

A germanium waveguide is formed from a P-type silicon substrate that is coated with a heavily-doped N-type germanium layer and a first N-type doped silicon layer. Trenches are etched into the silicon substrate to form a stack of a substrate strip, a germanium strip, and a first silicon strip. This structure is then coated with a silicon nitride layer.

In a method for electrically doping a semiconducting material, a layer of germanium is formed having a germanium layer thickness, while in situ incorporating phosphorus dopant atoms at a concentration of at least about 510.sup.18 cm.sup.3 through the thickness of the germanium layer during formation of the germanium layer. Additional phosphorus dopant atoms are ex situ incorporated through the thickness of the germanium layer, after formation of the germanium layer, to produce through the germanium layer thickness a total phosphorus dopant concentration of at least about 210.sup.19 cm.sup.3.

According to embodiments of the present invention, an optical device is provided. The optical device includes a substrate, a semiconductor layer on the substrate, the semiconductor layer having an initial tensile strain and including a monolithic crossbeam structure defined therein, and an optical cavity optically coupled to the monolithic crossbeam structure, wherein the monolithic crossbeam structure has a first beam and a second beam arranged at least substantially orthogonal to each other and intersecting each other at an intersection region, the intersection region being subjected to a tensile strain that is increased relative to the initial tensile strain. According to further embodiments of the present invention, a method of forming an optical device and a method of controlling an optical device are also provided.