Nils Weimann

Bio: Nils Weimann is an academic researcher from University of Duisburg-Essen. The author has contributed to research in topics: Heterojunction bipolar transistor & Bipolar junction transistor. The author has an hindex of 27, co-authored 160 publications receiving 7215 citations. Previous affiliations of Nils Weimann include Alcatel-Lucent & Agere Systems.

Transistor and manufacturing method therefor

Abstract: PROBLEM TO BE SOLVED: To provide a high-speed small-dimension heterobipolar transistor free from short circuit, and a manufacturing method therefor SOLUTION: A transistor comprises: a first compound semiconductor composition layer which is doped to have a first charge carrier polarity; a second compound semiconductor composition layer which is doped to have a second charge carrier polarity and is provided on the first layer; a third compound semiconductor composition layer which is doped to have the first charge carrier polarity and is provided on the second layer; a base electrode on the second layer; and a spacer ring which is interposed between the base electrode and the third layer and defines a charge carrier access path distance, within a range from approximately 200 Å to approximately 1000 Å, between the base electrode and the third layer COPYRIGHT: (C)2006,JPO&NCIPI

High-power linear balanced InP photodetectors for coherent analog optical links

Abstract: We demonstrated an integrated InP high-power dual pair balanced uni-traveling carrier photo-detector. Each pair delivers over 1 W of RF output power into a 50 Ω load at 2 GHz which is 6 dB higher than a discrete diode of the same junction diameter. The responsivity is 0.65 A/W and the common mode rejection ratio of the balanced diode pair was measured to be greater than 40 dB. The OIP3 was measured to be 48 dBm for one balanced pair of diodes. This balanced dual pair photo-detector is very well suited for enhancing the performance of coherent analog microwave photonic links.

Planar arrays op photodiodes electrically connected in series

Abstract: An apparatus includes a light detector (10). The light detector includes a substrate (16) with a planar surface (14) and an array of photodiodes (12k, 12k+1) located along the planar surface. Each photodiode (12k) has a sequence of different semiconductor layers stacked vertically over the planar surface. The photodiodes are electrically connected in series.

A 100 GHz fundamental oscillator with 25% efficiency based on transferred-substrate InP-DHBT technology

Abstract: A 96-GHz fixed-frequency fundamental oscillator with high efficiency is presented, realized using a transferred-substrate (TS) 0.8 μm InP-DHBT process. It delivers 9 dBm output power, with phase noise values of −90 dBc/Hz and −118 dBc/Hz at 1 MHz and 10 MHz offset frequency, respectively. DC consumption is only 30 mW from a 1.6 volts power supply, which corresponds to the highest overall DC-to-RF efficiency of a millimeter-wave frequency source reported to date.

Band parameters for III–V compound semiconductors and their alloys

Abstract: We present a comprehensive, up-to-date compilation of band parameters for the technologically important III–V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned relative to any other.

Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures

Abstract: Carrier concentration profiles of two-dimensional electron gases are investigated in wurtzite, Ga-face AlxGa1−xN/GaN/AlxGa1−xN and N-face GaN/AlxGa1−xN/GaN heterostructures used for the fabrication of field effect transistors. Analysis of the measured electron distributions in heterostructures with AlGaN barrier layers of different Al concentrations (0.15

AlGaN/GaN HEMTs-an overview of device operation and applications

Abstract: Wide bandgap semiconductors are extremely attractive for the gamut of power electronics applications from power conditioning to microwave transmitters for communications and radar. Of the various materials and device technologies, the AlGaN/GaN high-electron mobility transistor seems the most promising. This paper attempts to present the status of the technology and the market with a view of highlighting both the progress and the remaining problems.

Alternative Plasmonic Materials: Beyond Gold and Silver

Abstract: Materials research plays a vital role in transforming breakthrough scientific ideas into next-generation technology. Similar to the way silicon revolutionized the microelectronics industry, the proper materials can greatly impact the field of plasmonics and metamaterials. Currently, research in plasmonics and metamaterials lacks good material building blocks in order to realize useful devices. Such devices suffer from many drawbacks arising from the undesirable properties of their material building blocks, especially metals. There are many materials, other than conventional metallic components such as gold and silver, that exhibit metallic properties and provide advantages in device performance, design flexibility, fabrication, integration, and tunability. This review explores different material classes for plasmonic and metamaterial applications, such as conventional semiconductors, transparent conducting oxides, perovskite oxides, metal nitrides, silicides, germanides, and 2D materials such as graphene. This review provides a summary of the recent developments in the search for better plasmonic materials and an outlook of further research directions.

Gan : processing, defects, and devices

Abstract: The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.