MRS Meetings and Events


EQ01.09.04 2022 MRS Spring Meeting

Optimized Annealing for Activation of Implanted Si in β-Ga2O3

When and Where

May 12, 2022
2:30pm - 2:45pm

Hawai'i Convention Center, Level 3, 318B



Katie Gann1,Jonathan McCandless1,Michael Thompson1

Cornell University1


Katie Gann1,Jonathan McCandless1,Michael Thompson1

Cornell University1
Ion implantation for selective area doping is important for device structures and lowering contact resistance in Ga<sub>2</sub>O<sub>3</sub>. While there are reports of implant and activation of Si under N<sub>2</sub>, little has been done to narrow down the optimal time, temperature, and ambient conditions for annealing as well as the impact of a capping layer during implantation and annealing. To form a 100 nm box implant with a target concentration of 5x10<sup>19</sup> cm<sup>-3</sup>, Si was implanted at three energies (16-120 keV) with a total dose 7x10<sup>14</sup> cm<sup>-2</sup> into MBE grown UID β-Ga<sub>2</sub>O<sub>3</sub> films on Fe-doped semi-insulating β -Ga<sub>2</sub>O<sub>3</sub> substrates. A wide variety of annealing conditions was used for dopant activation and lattice recovery (with the best conditions yielding 88% activation with R<sub>s </sub>= 130 Ω/sq and μ = 72 cm<sup>2</sup>/Vs) using an ultrahigh vacuum quartz tube furnace with precise gas control and an extra drying step. Anneal times varied from 10 minutes to two hours and temperatures ranged from 850 to 1000 °C. Hall measurements showed that shorter times were optimal for activation and longer times resulted in “over annealing” and deactivation of the Si dopants. Highest activation was achieved between 900 and 950 °C with lower temperatures showing reduced mobility and higher temperatures showing reduced carriers as well as increased redistribution of Si, seen in Secondary Ion Mass Spectrometry profiles. While previous studies have shown a N<sub>2</sub> ambient to yield higher activation and reduced redistribution compared to O<sub>2</sub> conditions, by annealing under dried forming gas (4% H<sub>2</sub>/N<sub>2</sub>) and vacuum with poorer results, it is clear that a non-zero pO<sub>2</sub> and pH<sub>2</sub>O are needed for optimized electrical activity, and this processing window was identified using controlled gas mixtures. Recovery of Photoluminescence signal was found to be correlated with increased sheet resistance values and lattice recovery was gauged with Cathodoluminescence and Transmission Electron Microscopy.



Symposium Organizers

Robert Kaplar, Sandia National Laboratories
Srabanti Chowdhury, Stanford University
Yoshinao Kumagai, Tokyo University of Agriculture and Technology
Julien Pernot, University of Grenoble Alpes

Publishing Alliance

MRS publishes with Springer Nature