First principles calculations provide a defect phase diagram for gallium oxide

APR 09, 2018

New theoretical development suggests gallium oxide as a semiconductor material could be more ubiquitous by establishing phase diagrams over a wide variety of dopants and processing conditions to suppress defect states for high quality operation.

Drew DeJarnette

DOI: 10.1063/1.5033551

First principles calculations provide a defect phase diagram for gallium oxide internal name — First principles calculations provide a defect phase diagram for gallium oxide lead image

The age of new materials to replace or complement silicon as the go-to semiconductor is fast approaching. Compared with silicon, wide band gap materials enable higher switching voltages, higher efficiencies, and the ability to operate at higher temperatures. As a relatively new ultrawide band gap material considered for semiconductor devices, gallium oxide must undergo optimization, verification, and testing to ensure high quality and robustness, especially in regards to its charge-carrier concentration, which is the key property in a variety of applications.

In new work reported in APL Materials, first principles density functional theory helps determine the optimal dopant type, concentration, and process conditions for gallium oxide to generate a specific carrier density. The author created phase diagrams showing the net doping concentration for a variety of dopant species and processing conditions, allowing future researchers to better plan for device fabrication. This fundamental understanding is vital to minimizing the defects in gallium oxide semiconducting devices, which will enable breakthroughs in barriers that other materials such as silicon have not breached, or cannot.

The work indicates that silicon is the most promising dopant for n-type operation owing to its ideal dopant behavior. Carrier densities upwards of 10²⁰ per cubic centimeter are accessible at the predicted optimal dopant concentrations and thermodynamic conditions, while minimizing potentially detrimental defects.

These results provide a guide to optimize gallium oxide for the specific carrier concentration suitable for a desired application. The understanding opens new avenues to create tailored and stable properties for this emerging material, aiding the realization of its full potential as a ubiquitous new microelectronics material.

Source: “Defect phase diagram for doping of Ga₂O₃,” by Stephan Lany, APL Materials (2018). The article can be accessed at https://doi.org/10.1063/1.5019938 .