## 4 Conclusions  
In summary, a process was developed for the fabrication of buried locally gated graphene transistors with Al2O3 as a gate dielectric that can be suitable for not only flexible electronics but also LIG-based technology implementations. A new processing option was illustrated and presented with the use of TEOS as an etch stop for contact via etching of Al2O3. The proposed process is also compatible with other ALD materials such as HfO2 and TiO2. The process presented here resulted in Dirac points as low as 4 V with metal-to-graphene contact resistance as low as \(\sim\)1.7 k\(\Omega\cdot\)um. The hole mobility had an average of 457.97 cm\({}^{2}\)/V\(\cdot\)s with a non-uniformity of 93%. SEM, Raman, and AFM inspections were carried out to agree and validate that an inconsistent graphene channel area, degraded monolayer characteristic, and heavily roughened Al/Al2O3 surface were the main factors contributing to electrical performance non-uniformity. In addition, model fitting indicated that the extracted contact resistance values had a smaller variation than the extracted mobility values for each particular device when comparing each of the test conditions. This indicated that traps along the channel had a minimum impact on device variation and non-uniformity. On the other hand, there was large variation in the contact resistance values and mobility observed between devices, the latter still being a consequence of the Al roughness. The results presented demonstrate the need to reduce device variability and non-uniformity by improving not only transfer methods but also the use of smoother surfaces and compatible materials. The presented analysis provides a framework with \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Author** & **GFET Channel Structure** & **\# of Devices** & **Non-Uniformity** \\ \hline This work, 2023 & Local buried gate & 24 & \begin{tabular}{c} Dirac point: 6.7 V, NU: 59\% \\ \(\mu\): 457.97 cm\({}^{2}\)/V\(\cdot\)s, NU: 93\% \\ \end{tabular} \\ \hline [PERSON] et al., 2021 [38] & Dual top gate & 50 & \(\mu\): 60 cm\({}^{2}\)/V\(\cdot\)s, NU: 66.7\% \\ \hline [PERSON] et al., 2021 [24] & Top gate & 18 & \(\mu\): 2800 cm\({}^{2}\)/V\(\cdot\)s, NU: 10.7\% \\ \hline [PERSON] et al., 2019 [19] & Back gate, LIG & 10 & Average sensitivity (\(\Delta\)R/R\({}_{\text{He}}\)): 2.99, NU: 209\% \\ \hline [PERSON] et al., 2019 [61] & Back gate & 54 & \begin{tabular}{c} f\({}_{\text{T}}\): 8 GHz, NU: 75\% \\ f\({}_{\text{max}}\): 8 GHz, NU: 62.5\% \\ \end{tabular} \\ \hline [PERSON] et al., 2018 [62] & Back gate & 36 & \begin{tabular}{c} \(\mu\): 206 cm\({}^{2}\)/V\(\cdot\)s, NU: 63\% \\ \(\mu\)PMMA: 180 cm\({}^{2}\)/V\(\cdot\)s, NU: 542\% \\ \end{tabular} \\ \hline [PERSON] et al., 2017 [34] & Top gate & 4500 & \
\begin{tabular}{c} Dirac point: 4 V, NU: 150\% \\ \(\mu\): 40 cm\({}^{2}\)/V\(\cdot\)s, NU: 300\% \\ \end{tabular} \\ \hline [PERSON] et al., 2016 [36] & Back gate & \textgreater{}12,000 &
\begin{tabular}{c} Dirac point: 22.5, NU: 88\% \\ \(\mu\): 4945 cm\({}^{2}\)/V\(\cdot\)s, NU: 200\% \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Reported high-volume fabrication results of GFETs. which other researchers can analyze and correlate device variation and non-uniformities while methods to reduce variability are investigated. The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app13127201/s1](https://www.mdpi.com/article/10.3390/app13127201/s1)]([https://www.mdpi.com/article/10.3390/app13127201/s1](https://www.mdpi.com/article/10.3390/app13127201/s1)): Figure S1. (a) Dirac point voltage and (b) mobility distribution of 24 identical devices; Figure S2. (a) Overlay of \(\rm I_{D}V_{G}\) characteristics. (b) Raman of starting graphene on copper foil; Figure S3. IV curve of fabricated GFET without gate bias for ohmic behavior observation; Figure S4. \(\rm I_{D}\)-\(\rm V_{G}\) curve of (a) graphene GFET S-10 and (b) RIT Nanofab fabricated GFET with device dimensions of W/L = 100/80 \(\rm\upmu\)m; Table S1.