Abstract: A quantum well structure comprises a layered semiconductor definitive of a quantum well profile that contains at least two subbands characterized by an enhanced carrier conductivity difference between the subbands. The doping of the layered structure establishes a carrier population only within the lower-energy subband. A dynamic carrier population inversion between subbands is established by applying an external electric field in the plane of the quantum well. Light output from the structure results from intersubband transitions. In one device embodiment, the carriers comprise electrons, the subband profile is within the conduction band, and the quantum well profile comprises a nested quantum well profile. In another device embodiment, the carriers comprise holes, the subband profile is within the valence band, and the quantum well profile comprises a strained quantum well profile. One important application for such devices is as a far-infrared or submillimeter light source.

Abstract: An InGaAs semiconductor device implemented on a semiconductor substrate having a first major surface on which active semiconductor devices are to be formed, and a second major surface. An etch stop layer is provided on the first major surface. A layer of semiconductor material is provided on the etch stop layer and portions of the substrate are selectively removed to provide a pattern of apertures in the layer extending to the etch stop layer. Dopant species are provided through the second major surface to form active regions in the layer of semiconductor material. The resulting structure permits the integration of optoelectronic devices with photoelectronic devices on the same substrate.

Abstract: A process for fabricating a semiconductor device or a semiconductor substrate having a first major surface on which active semiconductor devices are to be formed, and a second major surface. An etch stop layer is provided on the first major surface. A layer of semiconductor material is deposited on the etch stop layer and portions of the substrate are selectively removed to provide a pattern of apertures in the layer extending to the etch stop layer. Dopant species are provided through the second major surface to form active regions in the layer of semiconductor material.