N. von den Driesch

Role of MgO barriers for spin and charge transport in Co/MgO/graphene nonlocal spin-valve devices

We investigate spin and charge transport in both single and bilayer graphene non-local spin-valve devices. Similar to previous studies on bilayer graphene, we observe an inverse dependence of the spin lifetime on the carrier mobility in our single layer devices. This general trend is only observed in devices with large contact resistances. Furthermore, we observe a second Dirac peak in devices with long spin lifetimes. This results from charge transport underneath the contacts. In contrast, all devices with low ohmic contact resistances only exhibit a single Dirac peak. Additionally, the spin lifetime is significantly reduced indicating that an additional spin dephasing occurs underneath the electrodes.

Negative differential resistance in direct bandgap GeSn p-i-n structures

Certain GeSn alloys are group IV direct bandgap semiconductors with prospects for electrical and optoelectronical applications. In this letter, we report on the temperature dependence of the electrical characteristics of high Sn-content Ge0.89Sn0.11 p-i-n diodes. NiGeSn contacts were used to minimize the access resistance and ensure compatibility with silicon technology. The major emphasis is placed on the negative differential resistance in which peak to valley current ratios up to 2.3 were obtained. TCAD simulations were performed to identify the origin of the various current contributions, providing evidence for direct band to band tunneling and trap assisted tunneling.

Suppression of contact-induced spin dephasing in graphene/MgO/Co spin-valve devices by successive oxygen treatments

By successive oxygen treatments of graphene nonlocal spin-valve devices we achieve a gradual increase of the contact-resistance\char21{}area products

Low Temperature Deposition of High-k/Metal Gate Stacks on High-Sn Content (Si)GeSn-Alloys

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Performance benchmarking of p-type In 0.65 Ga 0.35 As/GaAs 0.4 Sb 0.6 and Ge/Ge 0.93 Sn 0.07 hetero-junction tunnel FETs

of Co/MgO spin injection and detection electrodes and a transition from linear to nonlinear characteristics in the respective differential

Correlation of bandgap reduction with inversion response in (Si)GeSn/high-k/metal stacks.

dV\text{\ensuremath{-}}dI

Quantum confinement effects in GeSn/SiGeSn heterostructure lasers

curves. With this manipulation of the contacts, both spin lifetime and the amplitude of the spin signal can significantly be increased by a factor of seven in the same device. This demonstrates that contact-induced spin dephasing is the bottleneck for spin transport in graphene devices with small

GeSn lasers for monolithic integration on Si

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The thermal stability of epitaxial GeSn layers

values. With increasing

Silicon tunnel FET with average subthreshold slope of 55mV/dec at low drain currents

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