Enhanced Transport and Transistor Performance with Oxide Seeded High-κ Gate Dielectrics on Wafer-Scale Epitaxial Graphene

Abstract

We explore the effect of high-κ dielectric seed layer and overlayer on carrier transport in epitaxial graphene. We introduce a novel seeding technique for depositing dielectrics by atomic layer deposition that utilizes direct deposition of high-κ seed layers and can lead to an increase in Hall mobility up to 70% from as-grown. Additionally, high-κ seeded dielectrics are shown to produce superior transistor performance relative to low-κ seeded dielectrics and the presence of heterogeneous seed/overlayer structures is found to be detrimental to transistor performance, reducing effective mobility by 30-40%. The direct deposition of high-purity oxide seed represents the first robust method for the deposition of uniform atomic layer deposited dielectrics on epitaxial graphene that improves carrier transport.

Dielectric environment effect on carrier mobility of graphene double-layer structure

“…14,15 Indeed, several electronic transport measurements on graphene or atomically thin material have successfully revealed mobility enhancement though change in the dielectric environment. [16][17][18][19] However, a systematic study of the dielectric environment effect on the carrier mobility of the GDLS has not been performed yet.…”

Microstructure Effects on the Water Oxidation Activity of Co3O4/Porous Silica Nanocomposites

“…The carrier mobility in 1-D and 2-D semiconductor nanostructures is sensitive to permittivity, 77 as is that of single-layer graphene transistors in different dielectric environments. 78,79 The catalytic activities of surface-modified and unmodified Co 3 O 4 /SBA-15 nanocomposites were also measured for comparison ( Figure 8 and Table 3). The concentration of O 2 produced using Co 3 O 4 /SBA-15 nanocomposites reached a maximum yield within 50−60 min, which is consistent with the aforementioned and with prior reports.…”

Effect of ferroelectric substrate on carrier mobility in graphene field-effect transistors

“…10 The screening effect has been demonstrated experimentally by examples of the G-FETs with high k HfO 2 and ferroelectric PZT as the top and back gate, respectively. 13,19 The G-FET on PZT reveals carrier mobility up to 70 000 cm 2 /V s in a fewlayer graphene at room temperature. 19 In both cases, the charged impurities are assumed to be located inside or at the interface of the high dielectric constant material, such as oxygen vacancies in HfO 2 , or adsorbates on the PZT surface.…”

“…For instance, the charged impurities can be associated with water molecules trapped at the graphene-substrate interface or with the oxygen vacancies in the gate dielectric. [11][12][13] Noncontrollable concentration and spatial inhomogeneity of the charged impurities result in that the mobility in the G-FETs is typically well below the highest reported values (Refs. 9 and 14-18), the residual carrier concentration is high, it is non-reproducible, and spatially distributed over the wafer surface.…”