Graphene growth through a recrystallization process in plasma enhanced chemical vapor deposition

Abstract

Thermal chemical vapor deposition (TCVD) is the current method of choice to fabricate high quality, large area graphene films on catalytic copper substrates. In order to obtain sufficiently high growth rates at reduced growth temperatures an efficient dissociation of the precursor molecules already in the gas phase is required. We used plasma enhanced chemical vapor deposition (PECVD) to fabricate high quality graphene films at various temperatures. The efficient, plasma-induced dissociation of the precursor molecules results in an activation energy of 2.2 eV for the growth rate in PECVD, which is reduced by almost a factor of 2 compared to TCVD growth in the same reactor. By varying the growth time, we demonstrate that crystalline graphene grains surrounded by amorphous carbon formed during the early stage of growth merge into an almost defect-free graphene film with growth time via a recrystallization process. Almost defect-free graphene is prepared with negligible (I /I < 0.1) contributions of the D peak in Raman spectroscopy and with a sheet resistance down to 470 Ω/sq.

Direct growth of graphene on Ge(100) and Ge(110) via thermal and plasma enhanced CVD

“…5 e,f), however, corresponds to a work function of ~ 5.2 eV. This value is close to theoretical values of amorphous carbon 59 , thus indicating the formation of a defective carbon layer around the crystalline graphene flakes in PECVD, similar to what is reported in literature for PECVD grown graphene on Cu 60 .…”

“…Note that for each process a fresh foil was used. Details of the process and the sacrificial foil are discussed in more detail elsewhere 60 . The chamber pressure was adjusted to 4 mbar at a constant temperature of 757 °C.…”

Direct growth of graphene on GaN via plasma-enhanced chemical vapor deposition under N2 atmosphere

“…It is known that a PECVD process has a higher dissociation of the carbon containing precursors compared to thermal CVD due to the physical component of collisions between free electrons, atoms and molecules [42]. The higher dissociation can result in higher growth rates of graphene [14,37]. Due to this plasma-enhanced dissociation, the growth rate can be adjusted by varying the concentration of the carbon containing source (e.g.…”

“…All processes in this work were done with a plasma power of 40 W and a pulse frequency of 10 kHz. More details about the pulsed DC plasma and the plasma process are described elsewhere [37].…”