Enhanced Intrinsic Voltage Gain in Artificially Stacked Bilayer CVD Graphene Field Effect Transistors

Abstract

We report on electronic transport in dual-gate, artificially stacked bilayer graphene field effect transistors (BiGFETs) fabricated from large-area chemical vapor deposited (CVD) graphene. The devices show enhanced tendency to current saturation, which leads to reduced minimum output conductance values. This results in improved intrinsic voltage gain of the devices when compared to monolayer graphene FETs. We employ a physics based compact model originally developed for Bernal stacked bilayer graphene FETs (BSBGFETs) to explore the observed phenomenon. The improvement in current saturation may be attributed to increased charge carrier density in the channel and thus reduced saturation velocity due to carrier-carrier scattering.

All CVD Boron Nitride Encapsulated Graphene FETs With CMOS Compatible Metal Edge Contacts

“…The transistors show an I ON /I OFF current ratio of ∼6, mobility values ranging from 1000 to 5000 cm 2 /V • s, extracted contact and sheet resistance values of ∼2 k • μm and ∼750 /sq., respectively, and quasi-saturating output characteristics. The low dc output conductance values observed in these devices are found to be lower than the conventional monolayer graphene on SiO 2 FETs, and are comparable to artificially stacked bilayer graphene (ASBLG) FETs, which have been recently proposed as an improvement over monolayer GFETs for obtaining enhanced intrinsic voltage gain performance [36]. These aspects are cumulatively exploited in demonstrating a voltage amplifier circuit application based on these GFETs which yield a voltage gain of up to ∼6 dB in a resistive load scheme.…”

“…In addition, poor current saturation in the output characteristics (source-drain current I DS versus source-drain voltage V DS ) of single layer GFETs is a well-known bottleneck that results in poor voltage gain and limits f Max performance [35]. Good current saturation, i.e., lower g ds , improves this situation, and is thus the desired quantity [36], [37]. For this, exfoliated hBN encapsulated monolayer graphene devices with strongly quasi-saturating output characteristics have been suggested in [8].…”

High Voltage Gain Inverters From Artificially Stacked Bilayer CVD Graphene FETs

“…Even though there have been several reports of large area growth of Bernal stacked bilayer graphene [14]- [16], the device performance obtained from such grown material was found to be largely varying [15]. Recently, we have reported improved voltage gain in FETs made with channels of artificially stacked bilayer graphene (ASBLG), which we attributed to enhanced carrier-carrier scattering under certain biasing conditions [17]. In this letter, we demonstrate and discuss inverters made from ASBLG fabricated by stacking two single layers of graphene (SLG), grown in-house using a thermal CVD method [18].…”

“…Contact metal in all devices was 100 nm thick e-beam evaporated gold (Au). Device fabrication details can be found in [17].…”

Eletroquímica e propriedades estruturais do grafeno em bicamada >i<on-chip>/i<

“…(folha de grafeno superior) estão exatamente dispostos acima dos átomos de carbono B da folha 1 (folha de grafeno inferior). Os átomos de carbono B da folha 2 se localizam no centro do hexágono formado pela configuração de átomos de carbono da folha 1, [64][65][66] como na Figura 4a.…”