Table 1.

The critical device performance parameters of top-gated graphene transistors at V_ds = 1V. The relevant data were extracted from a few representative literatures with the transconductance g_m scaled to V_ds= 1V assuming a linear I_ds-V_ds relation. The transit time is calculated using τ_t=g_m/C_TG. Since the channel length of our sub-100 nm device is less than the typical carrier mean free path in graphene (~ 1 micron),¹,³³ it is not straightforward to determine the carrier mobility values using a diffusive transport model. The mobility value cited for the device with self-aligned nanowire gate is based on our previous studies on longer channel devices using physically assembled oxide nanoribbons as the top-gate dielectrics, in which the carrier mobility >10,000 cm²/Vs are routinely achieved in top-gated grapheme transistors.¹⁴

Top-gate dielectric deposition approach	Mobility (cm2/Vs)	gm@Vds=1V (mS/µm)	CTG (nf/cm2)	Lgate (nm)	τt=gm/CTG @Vds=1V (ps)
ALD Al2O3 with NO2 functionalization7	400	0.025	556	360	80.1
ALD Al2O3 with Al buffer layer23	2700	0.275	400	350	5.09
ALD HfO2 with polymer buffer layer24	~1500	0.14	194	240	3.39
Self-aligned nanowire top-gate	>1000014	2.3	483	90	0.19