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.

A 200 mW InP DHBT W-band power amplifier in transferred-substrate technology with integrated diamond heat spreader

Abstract: A power amplifier in 800 nm transferred-substrate InP DHBT technology is presented in this paper. The technology used in this work features an integrated diamond heat sink layer that has significant impact on the reduction of thermal resistance. This increases the DC-power limit as well as RF output power for the same transistor periphery. The power amplifier delivers 200 mW output power at 87 GHz, for a total emitter periphery of 96 µm, at a peak PAE of 20 % and for more than 25 GHz 3-dB bandwidth.

An active balanced up-converter module in InP-on-BiCMOS technology

Abstract: This paper presents an active up-converter realized as hetero-integrated module in InP-on-BiCMOS technology. It consists of a fundamental Voltage Controlled Oscillator (VCO) in 0.25 μm BiCMOS technology and a frequency multiplier followed by double balanced Gilbert mixer cell in 0.8 μm transferred substrate (TS) InP-HBT technology, which is integrated on top of the BiCMOS MMIC. The fundamental VCO operates at 54 GHz. The module achieves a single-sideband (SSB) power up-conversion gain of 2.5 dB and −3.5 dB at 82 GHz and 106 GHz, respectively. It exhibits > 25 GHz IF bandwidth. To the knowledge of the authors, this is the first heterointegrated module reported so far.

A 315 GHz reflection-type push-push oscillator in InP-DHBT technology

Abstract: A 315-GHz reflection-type push-push oscillator is presented. It is realized using a 0.8 μm-emitter transferredsubstrate (TS) InP-DHBT technology with an fmax of 320 GHz. The oscillator delivers −10 dBm output power. DC consumption is only 21 mW from a 1.6 volts power supply, which corresponds to 0.5 % overall DC-to-RF efficiency.

Apparatus with improved layers of group III-nitride semiconductor

Abstract: An apparatus includes a crystalline substrate having a top surface, a crystalline semiconductor layer located on the top surface, and a plurality of dielectric regions. The crystalline semiconductor layer includes group III-nitride and has first and second surfaces. The first surface is in contact with the top surface. The second surface is separated from the top surface by semiconductor of the crystalline semiconductor layer. The dielectric regions are located on the second surface. Each dielectric region is distant from the other dielectric regions and covers an end of an associated lattice defect. Each lattice defect threads the crystalline semiconductor layer.

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.