Jakub Kierdaszuk, Ewelina Rozbiegała, Karolina Piętak, Sebastian Złotnik, Aleksandra Przewłoka, Aleksandra Krajewska, Wawrzyniec Kaszub, Maria Kamińska, Andrzej… 展开作者
Jakub Kierdaszuk, Ewelina Rozbiegała, Karolina Piętak, Sebastian Złotnik, Aleksandra Przewłoka, Aleksandra Krajewska, Wawrzyniec Kaszub, Maria Kamińska, Andrzej Wysmołek, Johannes Binder, Aneta Drabińska
By using four layered graphene/gallium nitride (GaN) Schottky diodes with an undoped GaN spacer, we demonstrate highly effective gating of graphene at low bias rendering this type of structure very promising for potential applications. An observed Raman G band position shift larger than 8.5 cm-1 corresponds to an increase in carrier concentration of about 1.2x10^13 cm-2. The presence of a distinct G band splitting together with a narrow symmetric 2D band indicates turbostratic layer stacking and suggests the presence of a high potential gradient near the Schottky junction even at zero bias. The subbands characterized by the highest Raman energies correspond to the largest concentration of electrons. An analysis based on electroreflectance measurements and a modified Richardson equation confirmed that graphene on n-GaN separated by an undoped GaN spacer behaves like a capacitor at reverse bias. At least 60% of G subband position shifts occur at forward bias, which is related to a rapid reduction of electric field near the Schottky junction. Raman micromapping shows a high uniformity of gating efficiency on the surface. Therefore, our studies demonstrate the usefulness of few layer turbostratic graphene deposited on GaN for tracing electron-phonon coupling in graphene. Multilayer graphene also provides uniform and stable electric contacts. Moreover, the observed bias sensitive G band splitting can be used as an indicator of charge transfer in sensor applications in the low bias regime.
Nano selective area growth of GaN by MOVPE on 4H-SiC using epitaxial graphene as a mask: towards integrated III-nitride / graphene / SiC electronics and optoelectronics
Stacking and electric field effects on the electronic properties of the layered GaN
在van der Waals-密度泛函理论的框架下研究了GAN原子层的稳定性和电子性质。我们发现层状GAN的基态是一个平面的类石墨烯结构，而不是一个弯曲的块状结构。应用外部垂直电场的层状GAN诱导不同的堆叠依赖的功能的带隙的可调谐性;单层的带隙不改变，而三层GAN的显着降低为0.4 V/mA的外加电场。有人建议，这种堆叠依赖的可调谐性的带隙中存在的一个施加的字段可能会导致新的应用程序的设备的基础上的层状GAN。
