High Gain Graphene Based Hot Electron Transistor with Record High Saturated Output Current Density

Abstract Hot electron transistors (HETs) represent an exciting new device for integration into semiconductor technology, holding the promise of high‐frequency electronics beyond the limits of SiGe bipolar hetero transistors. With the exploration of 2D materials such as graphene and new device architectures, hot electron transistors have the potential to revolutionize the landscape of modern electronics. This study highlights a novel hot electron transistor structure with a record output current density of 800 A cm−2 and a high current gain α, fabricated using a scalable fabrication approach. The hot electron transistor structure comprises 2D hexagonal boron nitride and graphene layers wet transferred to a germanium substrate. The combination of these materials results in exceptional performance, particularly in terms of the highly saturated output current density. The scalable fabrication scheme used to produce the hot electron transistor opens up opportunities for large‐scale manufacturing. This breakthrough in hot electron transistor technology holds promise for advanced electronic applications, offering high current capabilities in a practical and manufacturable device

Magnetic structure and multiferroic coupling in pyroxene NaFeSi2O6

By comprehensive neutron diffraction measurements we have studied the magnetic structure of aegirine (NaFeSi2O6) in and above its multiferroic phase. Natural aegirine exhibits two magnetic transitions into incommensurate magnetic order with a propagation vector of (k) over right arrow (inc) = (0, similar to 0.78,0). Between 9 and 6 K, we find a transverse spin-density wave with moments pointing near the c direction. Below 6 K, magnetic order becomes helical and spins rotate in the ac plane. The same irreducible representation is involved in the two successive transitions. In addition, the ferroelectric polarization (P) over right arrow appearing along the b direction cannot be described by the most common multiferroic mechanism but follows (P) over right arrow proportional to ($) over right arrow (i) x (S) over right arrow (j). Synthetic NaFeSi2O6 does not exhibit the pure incommensurate helical order but shows coexistence of this order with a commensurate magnetic structure. By applying moderate pressure to natural aegirine, we find that the incommensurate magnetic ordering partially transforms to the commensurate one, underlining the nearly degenerate character of the two types of order in NaFeSi2O6