Abstract: The invention includes methods of fabricating a bipolar transistor that adds a silicon germanium (SiGe) layer or a third insulator layer of, e.g., high pressure oxide (HIPOX), atop an emitter cap adjacent the intrinsic base prior to forming a link-up layer. This addition allows for removal of the link-up layer using wet etch chemistries to remove the excess SiGe or third insulator layer formed atop the emitter cap without using oxidation. In this case, an oxide section (formed by deposition of an oxide or segregation of the above-mentioned HIPOX layer) and nitride spacer can be used to form the emitter-base isolation. The invention results in lower thermal cycle, lower stress levels, and more control over the emitter cap layer thickness, which are drawbacks of the first embodiment. The invention also includes the resulting bipolar transistor structure.

Abstract: A terahertz (THz) frequency radiation source to emit radiation in a narrow wavelength band within a range of about 3 ?m to 3000 ?m. This source includes: a broad bandwidth emitter to generate a broad bandwidth emitted wavelength band within the wavelength range; a first planar waveguide optically coupled to the broad bandwidth emitter to transmit the broad bandwidth radiation; a disk resonator evanescently coupled to the first planar waveguide with a resonance wavelength band within the emitted wavelength band; and a second planar waveguide evanescently coupled to the disk resonator to transmit radiation in the narrow wavelength band. The emitted wavelength band has a bandwidth greater than or equal to about 0.01 times a mid-band wavelength. The resonance wavelength band has a resonance wavelength bandwidth of less than or equal to about 0.25 times the emitted bandwidth. The narrow wavelength band is substantially equal to the resonance wavelength band.

Abstract: The invention includes methods of fabricating a bipolar transistor that adds a silicon germanium (SiGe) layer or a third insulator layer of, e.g., high pressure oxide (HIPOX), atop an emitter cap adjacent the intrinsic base prior to forming a link-up layer. This addition allows for removal of the link-up layer using wet etch chemistries to remove the excess SiGe or third insulator layer formed atop the emitter cap without using oxidation. In this case, an oxide section (formed by deposition of an oxide or segregation of the above-mentioned HIPOX layer) and nitride spacer can be used to form the emitter-base isolation. The invention results in lower thermal cycle, lower stress levels, and more control over the emitter cap layer thickness, which are drawbacks of the first embodiment. The invention also includes the resulting bipolar transistor structure.

Abstract: An electrically-pumped terahertz (THz) frequency radiation source (or detector), including an optical gain (or absorption) material with two electrodes electrically coupled to the optical gain material. The optical gain (or absorption) material is formed substantially of at least one group IV element and doped with at least one dopant, which has an intra-center transition frequency in a range of about 0.3 THz to 30 THz. Also, a method of manufacturing electrically-pumped THz frequency radiation sources (or detectors).

Abstract: A terahertz (THz) frequency radiation source to emit radiation in a narrow wavelength band within a range of about 3 &mgr;m to 3000 &mgr;m. This source includes: a broad bandwidth emitter to generate a broad bandwidth emitted wavelength band within the wavelength range; a first planar waveguide optically coupled to the broad bandwidth emitter to transmit the broad bandwidth radiation; a disk resonator evanescently coupled to the first planar waveguide with a resonance wavelength band within the emitted wavelength band; and a second planar waveguide evanescently coupled to the disk resonator to transmit radiation in the narrow wavelength band. The emitted wavelength band has a bandwidth greater than or equal to about 0.01 times a mid-band wavelength. The resonance wavelength band has a resonance wavelength bandwidth of less than or equal to about 0.25 times the emitted bandwidth. The narrow wavelength band is substantially equal to the resonance wavelength band.