A non-invasive gating method for probing 2D electron systems on pristine, intrinsic H-Si(111) surfaces

摘要

Intrinsic Si(111) surfaces passivated with atomic hydrogen are an ideal platform to host two-dimensional electron systems. Traditional methods to probe these surfaces, however, typically involve the placement of dopants and metals directly onto the surface and subsequent high temperature processing, which can be harsh and invasive and lead to surface degradation. Here, we detail a non-invasive gating approach for probing two-dimensional electron systems on intrinsic H-Si(111) surfaces using a silicon-on-insulator (SOI) gating assembly. In this architecture, all harsh device fabrication is performed on a single SOI chip, ensuring that the H-Si(111) surface remains in pristine condition, or as close to the original manufactured intrinsic-Si wafer as possible. To achieve this, we intentionally keep our H-Si(111) surfaces free of any dopants or metals, which are instead placed on the adjacent SOI chip. All electrical components, including Ohmic contacts and accumulation and depletion gates, are housed in the SOI piece. The Ohmic contacts on the SOI piece are brought into physical and electrical contact with the pristine H-Si(111) piece after being van der Waals bonded at room temperature, while all gates on the SOI piece are separated from the H-Si(111) surface by vacuum. Architecture details, baseline operation tests, and 77K device characterization measurements will be discussed, as well as the implications of going beyond H-Si(111) surfaces and using our device architecture to facilitate transport measurements on halogen-terminated Si surfaces.