April 22 - 26, 2024
Seattle, Washington
May 7 - 9, 2024 (Virtual)

Event Supporters

2024 MRS Spring Meeting
EL04.09.06

First-principles calculations on point defects and doping in (Al,Ga)2O3 ultrawide-band gap semiconductors

When and Where

Apr 25, 2024
10:45am - 11:15am
Room 345, Level 3, Summit

Presenter(s)

Co-Author(s)

Joel Varley1

Lawrence Livermore National Laboratory1

Abstract

Joel Varley1

Lawrence Livermore National Laboratory1
Semiconductor devices utilizing ever-wider band gap materials have the promise of more compact and efficient energy conversion that can help accelerate the transformation to an energy infrastructure based primarily on renewable resources. Gallium oxide and related alloys are rapidly developing as promising material platforms for next-generation power electronics owing to their large, tunable band gaps, controllable electrical conductivity, and commercially-available single-crystal substrates that can be grown via a number of industrially-scalable processes. Analogous to the AlGaN system, the incorporation of Al into Ga<sub>2</sub>O<sub>3</sub> to form (Al<i><sub>x</sub></i>Ga<sub>1-x</sub>)<sub>2</sub>O<sub>3</sub> (AGO) alloys can lead to a significant increase of the band gap, but spanning a much larger rage of ~4.8 eV-8.6 eV. AGO also exhibits the possibility of different crystal structures and lattice constants, leading to a number of possible epitaxial relationships beyond the wurtzite AlGaN system. Despite this promise, a number of questions remain as to the effectiveness of donor doping and how to overcome the possibility of compensation in the limit high Al-contents, similar to that in AlGaN. Here we assess <i>n</i>-type doping of Ga<sub>2</sub>O<sub>3</sub> and consider the prospects of doping in the larger-gap Al-containing alloys using first-principles modelling approaches based on hybrid functional calculations. We consider a number of conventional dopants such as Si, Ge and Sn, as well as lesser-explored transition-metal donor dopants that have been identified as effective alternatives. We additionally consider the role of native cation vacancies, which are known to be potentially problematic sources of compensation. Our results identify composition regimes in AGO alloys that may be most effectively targeted for increased band gaps and effective donor doping, with composition regimes specific to particular dopant species. These results provide guidance for doping in Ga<sub>2</sub>O<sub>3</sub> and related alloys incorporated into heterostructure devices.<br/>This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the LLNL Laboratory Directed Research and Development funding under project number 22-SI-003 and the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. DOE, Office of Energy Efficiency and Renewable Energy, Advanced Materials and Manufacturing Office.

Symposium Organizers

Hideki Hirayama, RIKEN
Robert Kaplar, Sandia National Laboratories
Sriram Krishnamoorthy, University of California, Santa Barbara
Matteo Meneghini, University of Padova

Symposium Support

Silver
Taiyo Nippon Sanso

Session Chairs

Sriram Krishnamoorthy
Joel Varley

In this Session