Benjamin Munstermann

High-Frequency Measurements on InAs Nanowire Field-Effect Transistors Using Coplanar Waveguide Contacts

In this paper, a 50-μm-pitch coplanar waveguide pattern for on-wafer high-frequency measurements on nanowire FET is used. The contact structure exhibits relatively large parasitic elements in comparison to the intrinsic device making a precise deembedding both necessary and challenging. A single InAs nanowire FET with a large gate length of 1.4 μm possesses after deembedding a maximum stable gain higher than 30 dB and a maximum oscillation frequency of 15 GHz. The gate length scaling of the nanowire transistor is modeled using the experimental transconductance data of a set of transistors and an analytical model. On this basis, both the device performance and the expectation of high-frequency measurements at small gate lengths are discussed.

Sensitive high frequency envelope detectors based on triple barrier resonant tunneling diodes

InP-based resonant tunneling diodes with symmetrical I/V-characteristics have shown their excellent high frequency performance for THz signal generation. We present a modification with an additional third barrier to create an unsymmetrical I/V-characteristic. With their large current densities and low capacitances these devices are promising candidates for zero bias high frequency envelope detectors. Based on simulations two layer stacks are grown by MBE technology. The fabricated devices were measured at dc- and high frequencies. First measurement results for the short circuit responsivity are discussed.

Coplanar Contact Pattern for single InAs Nanowire FET

We report on the development of coplanar contact pattern for the RF-characterisation of nanoscaled devices. A contact layout exhibiting a low parasitic capacitance is developed using electrostatic field theory calculations. The improved pad- and coupling capacitance has been experimentally verified based on scattering parameter measurements and small signal parameter extraction of a single nanowire transistor.

Characterization and modeling of zero bias rf-detection diodes based on triple barrier resonant tunneling structures

InP-based resonant tunneling diodes with symmetrical I/V-characteristics have shown their excellent high frequency performance for THz signal generation. For signal detection we present a device with an additional third barrier to create an unsymmetrical I/V-characteristic. Sensitivity measurements are performed and further improvements by scaling of the active device area are discussed. To allow SPICE based circuit simulation an approach for a large signal model is presented.

Large-Signal Performance of Resonant Tunnelling Diodes in K-Band Oscillators

The large signal behaviour of resonant tunnelling diodes (RTD) in K-band oscillators is investigated in order to optimize the RF-output power of RTD-based voltage controlled oscillators. Circuit simulations based on a scaleable large-signal RTD model are presented and different approaches to increase the RF-power are proposed. A new differential RTD-VCO-circuit in InP RTD/HBT technology with a wide tuning range is introduced, employing balanced RTD-pairs.

Optimized RTD-HBT VCO design based on large signal transient simulations

This paper presents an optimized RTD-HBT single ended voltage controlled oscillator topology with increased tuning range and improved frequency stability at 20 GHz oscillation frequency. By connecting the RTD to the emitter of an HBT, a larger voltage swing at the parallel resonator compared to the direct connection can be achieved. In addition the RTD-capacitance influence on the oscillation frequency can be suppressed efficiently. Transient assisted harmonic balance simulations promise an increased oscillation power by 2 dB and a doubled tuning range of about 3.2 GHz compared to the conventional RTD-HBT circuits.

Wavelength-selective receiver for simultaneous λ=1.3 µm and λ=1.55 µm RF optical transmission

We report on a dual-wavelength detector consisting of two stacked PIN-diodes with a common center terminal. The aspect of electrical and optical crosstalk in dependence of layer parameters is discussed and the RF-performance is investigated on fabricated devices up to 12GHz.