Using a gating device compatible with the scanning tunneling microscope (STM), we adjust the doping level in our molecular-beam epitaxy (MBE) films through a back gate, and observe the change in local density of states with STM. To develop the gating device, we measure the dielectric breakdown of hBN-SiO2 and Al2O3-SiO2, and transfer high-quality graphene on the devices. The films are then grown on the devices with MBE and studied with STM. We show how the STM compatible gate-tunable devices are developed, how the materials is grown on the devices, and STM spectrums on gated materials.