Atomically precise advanced manufacturing for 2D bipolar devices

Hydrogen Depassivation Lithography has become established as the method for atomic-precision patterning for 2D dopant-based devices, such as qubits and analog quantum simulators. Research thus far in this area has mostly been focused on patterning of n-type dopants, such as P and As. In this work, we describe the process for fabrication of bipolar dopant-based devices, such as p-n junctions and n-p-n bipolar junction transistors, which may have a number of advantages such as improved gain-bandwidth product and low-noise operation. The P-doped parts of the device are created first, and the B-doped parts are created subsequently, requiring atomically-precise alignment to the P-doped parts. To achieve the necessary patterning precision, we have developed various advances to conventional STMs, including corrections for piezo creep and hysteresis, automatic lattice alignment, and spectroscopic imaging methods to give strong contrast of surface and buried dopants. The overall process described here has become known as Atomically Precise Advanced Manufacturing (APAM), which offers far better patterning precision than conventional techniques such as e-beam lithography.