Cathodoluminescence Study of Damage Formation and Recovery in Si-ion-implanted β-Ga₂O₃

Abstract

Ion implantation and activation annealing are key processes in the creation of an ideal free carrier distribution in semiconductor devices. Ultra-wide-bandgap (UWBG) semiconductors, such as gallium oxide (Ga2O3) and aluminum nitride (AlN), have many advantages suitable for power-device applications. We implanted silicon (Si) at doses ranging from 1 × 10 11 to 1 × 10 15 cm −2 into β-Ga2O3 (−201) wafers, and annealed them at 800 and 1000 °C in N2 atmosphere. Secondary ion mass spectrometry (SIMS) and cathodoluminescence (CL) were used to evaluate the dopant profile and damage resulting from ion implantation. The CL intensity decreased rapidly with the dose. Even at a dose of 1 × 10 11 cm −2 , the intensity dropped by nearly half of its value for the bare wafer. The CL intensity recovered after annealing at all doses; however, the CL intensity did not fully recover even after annealing at 1000 °C. Moreover, the CL-depth profile at a dose of 1 × 10 15 cm −2 after annealing at 1000 °C showed pronounced intensity decay near the Si-diffused region. The CLintensity decay was strongly correlated with Si diffusion. This phenomenon suggests that high-temperature annealing at high dose not only activates the Si dopant through the interaction of the interstitial Si and Ga vacancies but also causes interstitial Si atoms to diffuse into deeper regions. CL spectroscopy is very sensitive to the implantation damage and can be used for optimization of ion implantation and annealing processes in β-Ga2O3.

Minority-carrier dynamics in β-gallium oxide probed by depth-resolved cathodoluminescence

“…Luminescence spectroscopy is a possible method for this purpose. There have been many studies on photoluminescence (PL) [36][37][38][39][40][41][42][43][44][45][46][47][48][49] and cathodoluminescence (CL) [28,33,[50][51][52][53][54][55][56][57][58][59][60], although most have been dedicated to qualitative defect characterization. Considering carrier dynamics, the lack of spatial or depth resolution in the luminescence technique limits the direct observation of carrier behavior.…”