Atomically Precise Manipulation of Silicon-Aluminum Interfaces for Improving Energy Performances in Microelectronic Devices

Existing optical and electronic devices, although in some cases scaled down to remarkable levels (few nanometer dimensions in state-of-the-art integrated circuits), are not considered to be truly atomically precise in nature. The goal of this Phase II project is to employ atomic precision in a type of material deposition process known as molecular beam epitaxy to produce a new generation of high-performance devices. Atomically precise crystal growth will be used to produce a new generation of ultra-thin single- crystal semiconductor-metal quantum heterostructures. These atomically precise heterostructures will enable new levels of performance in optoelectronic devices such as high sensitivity photodetectors, high-gain, and radiation hard electronic devices such as, 2D heterojunction bipolar transistors, and low-noise backplane amplifiers to support superconducting transmons in quantum computer applications. Since atomically precise heterostructures function at low-power levels, they will also be more energy efficient. One version of a quantum heterostructure fashioned as an epitaxial digital heterostructure (EDH) will be developed through a combination of ultra-clean ultra-high vacuum crystal growth (known as epitaxy) in conjunction with precisely dosed atomic hydrogen to facilitate atomically abrupt single-crystal interfaces that are free of defects. In Phase II of this project, ultra-thin single-crystal layers of the semiconductor silicon (Si) and the metal aluminum (Al) will be carefully deposited with lattice matching (the same atomic spacing) onto commercially available transparent, insulating yttria-stabilized zirconia (YSZ) single-crystal substrates. Crystal deposition temperatures and source material fluxes will be controlled so that interfaces are abrupt and unwanted alloy formation is avoided. The physical, electrical, and optical characteristics of these quantum heterostructures will be measured, analyzed, and benchmarked against existing material systems. This new material system will then be used to support a new low-noise, bipolar device called EDH 2D Bipolar Junction Transistor. Commercial applications include civilian and military markets where high-performance, low- power, atomically precise optoelectronic and electronic devices are needed.