Dominic A. Funke

High room-temperature optical gain in Ga(NAsP)/Si heterostructures

We analyze the modal gain of Ga(NAsP) multi quantum-well heterostructures pseudomorphically grown on (001) silicon substrate by metal-organic vapor-phase epitaxy. Using the variable stripe length method, we obtain high modal gain values up to 78 cm−1 at room temperature that are comparable to the values of common high quality III-V laser material. We find good agreement between experimental results and theoretically calculated gain spectra obtained using a microscopic model. The results underline the high potential of Ga(NAsP) as an active material for directly electrically pumped lasers on silicon substrate.

A CMOS 16k microelectrode array as docking platform for autonomous microsystems

A microelectrode array (MEA) system based on an active pixel architecture is presented, which has been fabricated in 180nm CMOS technology, featuring 16384 active pixels (36×36×m2). Each pixel consists of 4 electrodes (each 12×12μm2): two (connected together) for actuating and two for differential sensing. The pixels are arranged in a square grid of 4.6×4.6mm2. Schematic and layout of the MEA were generated by a SKILL script. The MEA is designed as a docking platform for charging and communicating with autonomous microsystems, called lablets, as well as combinatorial electrochemistry. Experiments in aqueous electrolyte solutions confirm the functionality of the MEA to fulfill the requirements of a flexible configuration of the pixels and the possibility of charging microsystems in a solution.

A 200 μm by 100 μm Smart Dust system with an average current consumption of 1.3 nA

In this paper we present a microscale “Smart Dust” type system with a volume of 200 μm × 100 μm × 10 μm, called lablet. The lablet contains a 20 Hz low power clock generator, a sensor, electric actuators and a simple finite state machine to implement a predefined response to the sensor input. The system operates with supply voltages ranging from 0.3 V to 1.8 V and is thus suitable to be supplied from a capacitor with decreasing voltage. An input rectifier allows powering the lablet independent of polarity. The average current consumption of the system was measured to be 1.3 nA when supplied from a capacitor with an initial voltage of 1.8 V. The system is intended to be used within electrolyte solutions. The small system scale allows the investigation of “pourable electronics”, a concept where large quantities of microsystems are deployed within a chemical solution to perform a predefined task. Several lablets have been designed and fabricated in a standard 180 nm CMOS process and the electrical functionality has been verified by contacting the lablet electrodes with multiple probe needles.

High modal gain in Ga(NAsP)/(BGa)((As)P) heterostructures grown lattice matched on (001) silicon

We present modal gain measurements in Ga(NAsP) heterostructures pseudomorphically grown on silicon substrate. Using the variable stripe length method we analyze the modal gain performance of an unprocessed single quantum well sample for different excitation densities. We obtain high modal gain values up to 55 cm-1 at room temperature. These values are comparable to those of common high quality laser material. This demonstrates the high optical quality of the new dilute nitride material Ga(NAsP) and underlines its candidacy for electrically pumped lasing on silicon substrate.

Photoluminescence and optical gain of Ga(NAsP) heterostructures pseudomorphically grown on silicon (001) substrate

The novel metastable dilute nitride material Ga(NAsP) is a very promising candidate for electrically pumped lasers on silicon because it can be pseudomorphically grown on silicon substrate. Here we investigate the optical properties of a series of multi-quantum well Ga(NAsP) samples grown lattice matched on GaP and Si substrates. Temperature and excitation resolved photoluminescence spectroscopy indicates a significant impact of disorder-induced carrier localization effects on the optical properties. On the other hand, optical gain measurements reveal high modal gain up to 80 cm−1 at room temperature and demonstrate the suitability of this new material as an active material for laser devices. A comparative analysis of optical gain and photoluminescence data demonstrates a strong impact of the barrier-growth conditions on the optical quality of the material.

Time-resolved photoluminescence and optical gain of Ga(NAsP) heterostructures pseudomorphically grown on silicon (001) substrate

The novel metastable dilute nitride material Ga(NAsP) is a very promising candidate for electrically pumped lasers on silicon because it can be pseudomorphically grown on silicon substrate. Here we investigate the optical properties of a series of multi-quantum well Ga(NAsP) samples grown lattice matched on GaP and Si substrates. Temperature and excitation resolved photoluminescence spectroscopy indicates a significant impact of disorder-induced carrier localization effects on the optical properties. On the other hand, optical gain measurements reveal high modal gain up to 80 cm−1 at room temperature and demonstrate the suitability of this new material as an active material for laser devices. A comparative analysis of optical gain and photoluminescence data demonstrates a strong impact of the barrier-growth conditions on the optical quality of the material.

Modal Gain Analysis of GaNAsP Heterostructures on Silicon

We present modal gain measurements of GaNAsP multiple quantum well structures grown lattice-matched on silicon using the stripe-length method. High modal gain values of up to 80 cm-1 are observed at room temperature.