Electronic properties of CVD graphene: The role of grain boundaries, atmospheric doping, and encapsulation by ALD

Abstract

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Grain boundaries and unintentional doping can have profound effects on graphene-based devices. Here we study these in detail for CVD grown poly-crystalline monolayer graphene with two significantly different grain size distributions centered around 10-25 mm and 100-400 mm. Although the two types of graphene are processed under identical conditions after growth, they show distinct transport properties in field effect transistor devices. While all asfabricated samples showed similar p-type doping, the smaller grain size type graphene with larger number of grain boundaries exhibit lower average mobility. In order to separate out the effects of grain boundaries and doping from ambient exposure on the transport properties, the devices were encapsulated with Al 2 O 3 by atomic layer deposition. The encapsulation of large grain samples thereby showed drastic improvements in the performance with negligible doping while the small grain samples are largely intolerant to this process. We discuss the implications of our data for the integrated manufacturing of graphene-based device platforms.

Catalyst Interface Engineering for Improved 2D Film Lift-Off and Transfer

“…This result is significantly higher than for the wet-transferred samples, which only show 1570 cm V –1 s –1 for large grain size and 461 cm V –1 s –1 for standard grain size graphene. In the case of wet transfer, we suggest that acid induced polymer cross-linking 16,43 and preferential residue accumulation along the grain boundaries 44−46 are the main contributors to the diminished performance. In particular, the case of cross-linking is avoided in the LOT-I process, as the samples are only in contact with a NaOH solution.…”

Bolometric detection of terahertz quantum cascade laser radiation with graphene-plasmonic antenna arrays

“…Each square has an area = 9 µm 2 shorting the gap between the antennas' arms. A final conformal di electric layer of 80 nm of Al 2 O 3 was then deposited on top of the sample via atomic layer deposition (ALD) in stop-flow mode using H 2 O/ TMA precursors, thus encapsulating the graphene [19,20]. This last step is crucial in order to reduce the hysteresis [21] and bring the Dirac point to bias voltages lower than 100-120 V which was observed in previous strongly p-doped samples.…”

Memristive Non-Volatile Memory Based on Graphene Materials

“…In general, it is easy to complete the deposition of a graphene monolayer onto a metal substrate, and the progress of this approach demonstrates the great potential of large-area single crystals [25,[46][47][48]. Growth techniques reported in the literature can be observed in Table 1, including chemical vapor deposition (CVD), atomic layer deposition (ALD), nucleation and growth, liquid-phase exfoliation (LPE), electrochemical exfoliation, and a solution process [6,[49][50][51][52][53][54][55][56][57][58]. Apart from graphene-based materials, some researchers like Zhang et al also focused on other 2D materials such as MoS 2 -based composites, which presented excellent performance in the application of memristive devices, similar to that using graphene-based materials [58].…”

“…Table 1. Comparison among main synthesis technologies and applications for graphene and its derivatives [6,[49][50][51][52][53][54][55][56][57][58].…”