## 1 Introduction
Likewise, the design and fabrication of graphene-based chemical and physical sensors require devices with graphene dimensions in the micrometer range [44] to provide enough sensing area [17]. While sensors do not require large mobility, they do require repeatability between devices for robust and consistent signals [18]. In both cases, due to the larger relative dimensions of the graphene channel (1-100 um), it is expected that these large-area devices will be more susceptible to material variations that have been observed and reported in the graphene transfer and/or synthesis process [24; 34]. For example, [PERSON] et al. reported the fabrication and testing of \(>\)12,000 global back gate GFET sensors with an average Dirac point and hole mobility of 22.5 V and 495 cm\({}^{2}\)/V-s, but non-uniformities of 88% and 200% [36]. The fabrication methods for larger-area sensor devices require that graphene be exposed to the stimuli; as such, a back-gated or buried-gate process is preferred. A buried-gate process not only provides the extra advantage and flexibility of being able to access each sensor individually on the same substrate but also assists in the decrease in parasitic source-to-gate and source-to-drain capacitance in comparison to global back gates. In a buried-gate process, aluminum can be used as the gate material as it is readily available, is inexpensive, and can be deposited in multiple ways (sputter, thermal, and e-beam evaporation). In addition, the gate dielectric does not need to be ultrathin, as higher bias levels may be required to obtain more robust signals [24]. As such, atomic layer-deposited (ALD) Al\({}_{2}\)O\({}_{3}\) is often used as a dielectric as it generally provides lower interface traps than other CVD-based dielectrics, a lower Dirac point, and more repeatable results [24]. The integration of a buried aluminum gate with an ALD Al\({}_{2}\)O\({}_{3}\) dielectric presents the challenge of etch compatibility when accessing the buried aluminum gate electrode. Although some have reported that the top Al\({}_{2}\)O\({}_{3}\) can be simply scratched away during testing [45], the general approach is to apply the Al\({}_{2}\)O\({}_{3}\) layer in a fluorine-based plasma etch, as it has excellent selectivity to the underlying aluminum [46; 47], a wet chemical etch in BOE, or a diluted resist developer [26; 48]. As a downside, the fluorinated plasma etch of Al\({}_{2}\)O\({}_{3}\) is slow with only CF\({}_{4}\) gas at an etch rate of 4.5 nm/min [47]. The inclusion of O\({}_{2}\) in etch gas can increase the etch rate [49] but it may become challenging to complete with a standard photoresist mask as the etch selectivity to any organic materials decreases. There are several methods to synthesize graphene [50]. Among these, chemical vapor deposition (CVD) on a copper substrate results in large-area and high-quality single-layer graphene [51]. This CVD-grown graphene on Cu can then be transferred onto any needed substrate through wet, dry, or other alternative methods, thus providing process flexibility [52]. Another synthesis method, laser-induced graphene (LIG), has recently attracted extensive interest for chemical and biological sensors [19; 50; 51]. LIG can be integrated with both resistive-based [19] and field-effect transistor-based devices [53], where the graphene channel is exposed for sensing applications. One of the great advantages of LIG synthesis is that it completely eliminates the need for a graphene transfer process. Graphene formed directly on a polyimide (PI) [54] or any cross-linked hybrid lignocellulosic [55] substrate via a laser writer offers the ability to achieve a minimum spatial resolution of 12 \(\upmu\)m and has been reported by [PERSON] et al. [56]. The synthesized LIG consists of multilayer graphene with a high porosity characteristic that provides a much larger surface area when compared to monolayer graphene, which is favorable for chemical sensing applications.