AlGaN/GaN HEMT Optimization Using the RoundHEMT Technology

in Physica Status Solidi A. Applied Research (2001), 188

The electrical characterization of epitaxially grown HEMT layer systems for device fabrication is commonly performed by Hall measurements. However, the ultimate characterization of a HEMT layer system is ... [more ▼]

The electrical characterization of epitaxially grown HEMT layer systems for device fabrication is commonly performed by Hall measurements. However, the ultimate characterization of a HEMT layer system is the transistor device itself. The RoundHEMT concept meets the need for a device technology with few fabrication steps that allows a fast feedback to epitaxy while providing an evaluation of important electrical and also processing data. Even though nearly identical Hall data on structures with different thickness and doping concentration of the AlGaN layers suggest similar device properties, the RoundHEMTs resolve remarkable differences in device performance. The best layer structure was used to fabricate HEMTs with IDS = 700 mA/mm, fT = 35 GHz, and fmax = 70 GHz for LG = 0.2 mm. [less ▲]

Fabrication of Laterally Displaced Porous Silicon Filters

in Thin Solid Films (2001), 382(2001), 218-221

Porous silicon superlattices have been used to manufacture laterally displaced dielectric filters with different optical properties on one substrate. Two different fabrication processes for two-colour ... [more ▼]

Porous silicon superlattices have been used to manufacture laterally displaced dielectric filters with different optical properties on one substrate. Two different fabrication processes for two-colour microfilter arrays are presented. Both methods overcome the problem of non-uniform optical properties of the well-known procedure where two filter stacks are grown one upon another, with subsequent partial removal of the upper filter by reactive ion etching. The novel methods give uniform optical properties of the two filter areas, profiting from the main property of the formation process of porous silicon: the formation of porous silicon occurs only at the porous silicon substrate interface. [less ▲]

Formation of laterally displaced porous silicon filters using different fabrication methods

in Proceedings of the 3rd International EuroConference on Advanced Semiconductor Devices and Microsystems (2000)