NaMLab was founded in 2006 as a public private partnership between Qimonda AG and TU Dresden. In the first year, NaMLab started as a research organization with 10 employees focused on material research for future memory devices. The company steadily expanded and today, NaMLab serves a growing list of world-wide partners. NaMLab’s research is contributing to the main challenges for our future society with respect to climate change, digitalization and mobility by placing sustainable, secure and intelligent electronic solutions into the core focus. With respect to the technical areas those solutions can be divided into three main activities:
This fifth bi-annual report covers the NaMLab activities in the two year period 2018 and 2019. In that time frame, NaMLab further extended its role as a leading scientific research organization bridging basic research to application and industry. The level of international attention both for the scientific and the industrial environment has further increased.
NaMLab’s research in the field of dielectrics is focused on flourite-structure ferroelectric materials, such as hafnium oxide, and their application in capacitors. The understanding of the main factors that control ferroelectricity in hafnium oxide, as well as the understanding of the degradation mechanism of such ferroelectric materials was further enhanced. The significance of the oxygen vacancy concentration for the stabilization of the ferroelectric phase was observed and unavoidable depolarization fields have been identified to have a major contribution to the polarization-voltage characteristics and the field cycling stability. Beyond, the research on dielectrics is strongly linked to the device oriented topics.
All three reconfigurable device concepts explored at NaMLab are currently under consideration for applications in both intelligent self-learning electronics as well as electronics with a higher inherent security.
In reconfigurable nanowire devices, the polarity of a field effect device can be controlled by applying a gate voltage to a dedicated programming gate. In the reporting period, the efforts to develop the concept up to the system level together with partners from TU Dresden have been further extended. An important ingredient on the technology side was the development of a top-down fabrication route that enables faster realization of more complex devices and circuits. A first ferroelectric Schottky barrier field effect transistor has been realized which further extends the reconfigurability of the device to the non-volatile regime.
The second topic in reconfigurable devices is field effect transistors based on ferroelectric hafnium oxide. Together with partners from Fraunhofer IPMS-CNT and GLOBALFOUNDRIES, NaMLab has pushed this concept since 2009. In the reporting period, NaMLab worked together with GLOBALFOUNDRIES and the NaMLab Spin‑Off FMC on the further development of the embedded FeFET technology at
GLOBALFOUNDRIES. Moreover, the focus shifted towards exploration of useful applications of ferroelectric hafnium oxide beyond semiconductor memories like negative capacitance field effect, neuromorphic computing and memory-in logic devices. The realization of both synapse and neuron circuits using FeFET devices were achieved. With respect to negative capacitance, NaMLab succeeded in the first measurement of the S‑curve of a ferroelectric using a pulsed measurement technique.
The third major reconfigurable device concept explored is resistive switching. Here, new aspects of the threshold switching in niobium oxide have been explored that enable circuit demonstrators for new computing paradigms.
The field of energy efficiency devices has three key topics, namely solar cells, batteries and GaN materials and devices. All three research activities aim on providing sustainable electronic solutions. The focus of the field of solar cells was the development of conducting passivation layers building upon NaMLab’s expertise in dielectric materials. Results showing the feasibility of the different components: conductivity and surface passivation have been successfully demonstrated. Based on the know-how in bottom-up nanowire fabrication, anodes for lithium-ion batteries were processed. In this reporting period a method to characterize the stability of silicon anodes using in-situ Raman spectroscopy was developed, which will be extended in the future.
In the field of gallium nitride materials and devices at the outpost in Freiberg, we were able to reproducibly fabricate crack-free doped HVPE GaN crystals that are suitable for wafering. At the same time, in the MBE activities high quality films that reflect the low dislocation density of the underlying layers can be achieved and heterostructures with an inherently absent 2DEG were reported for the first time. In the field of GaN devices, development the pseudo-vertical device was further optimized and a technique to extract the p-doping concentration in the bulk of the device using the body bias effect was established.
In summary, in the reporting period NaMLab could further strengthen its position in the core topics, contributing to the grand challenges of our modern society and therefore increased its reputation in both the scientific and industrial semiconductor communities. This is documented in the increasing number of partnerships with local and international industrial and research partners. Another impressive increase of citations of NaMLab’s scientific publications as well as a large number of invitations to leading scientific conferences like IEEE-IEDM, VLSI, MRS etc. document the high international visibility NaMLab has now achieved. The NaMLab team will built on the strong results accomplished in this reporting period and further extend its efforts to continuously contribute to shape the exciting and challenging world of micro- and nanoelectronics.
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NaMLab looks back on 15 years of history in 2021. In its first year, NaMLab started as a research organization with 10 employees focused on materials research for future memory devices. The company expanded steadily and today NaMLab has approximately 50 employees working in research and administration.
Scientists and their research topics
Dr. Uwe Schroeder (Senior Scientist)
Dr. Stefan Slesazeck (Senior Scientist)
- Hafnium Oxide Based Ferroelectric Memory
- Resistive Switching Devices
- Charge Trapping Devices
Dr. Jens Trommer (Senior Scientist)
- Nanowire Based Reconfigurable Transistor
- Single MOS Complementary Nanowire Circuits
- Parallel Nanowire Devices for Sensing and Logic
- Germanium Nanowire RFETs
Dr. Andre Wachowiak (Senior Scientist)
- Gallium Nitride – Hydride Vapor Phase Epitaxy (w/ S. Schmult (IHM))
- Gallium Nitride – Molecular Beam Epitaxy (w/ S. Schmult (IHM))
- Gallium Nitride Based Device Technology
- High-k Dielectrics on Gallium Nitride
Dr. Matthias Grube (Senior Scientist)
- Nanoelectrodes for Li Batteries
- Passivation Layers for Solar Cells
- Heterojunction Metal Wrap Through Solar Cells
- Photoconductivity: 2D Mapping of Fixed Charges