100 MeV Ag and 25 keV He ion-beam induced defects in 4H-SiC

Abstract

Abstract

4H-SiC based power devices are driving a fundamental change in power electronics because of their outstanding physical and electrical characteristics, which also meet the requirements for military systems [1]. SiC technology is expected to replace silicon in a variety of applications as it can function at greater temperatures, voltages, and frequencies [2]. While silicon has a bandgap of around 1.12eV, silicon carbide has an almost threefold higher value ~3.23eV. Although silicon is the most extensively used semiconductor in electronics, it exhibits certain limitations, particularly in high-power applications since the bandgap provided by the semiconductor is an important element in these applications. Recent attempts that were made to enhance the efficiency and range of electric vehicles while reducing the weight and cost of the complete vehicle and therefore improving the power density of control electronics, the notion of employing SiC for such vehicles came into the picture [3]. SiC is a great answer to these emerging market requirements because of its unique physical characteristics [1-3]. Lately, SiC has also gained popularity as an alternative material for scalable and integrated quantum photonics as it can host several defects, the so-called colour centres, inside its bandgap [4]. Quantum characteristics related to single-photon emission and coherent spin state control have been demonstrated for several of these colour centres.

The SiC-based technology employs the super-junctions that are formed by creating p-type, high-aspect-ratio columns in n-doped vertical drift zones [5]. The growing demands for SiC power devices require mass production of super-junctions. Currently, the manufacturing of SiC super junctions deploys an advanced approach, whereby an extended implanted ion profile is achieved using monoenergetic MeV ions. The technique of ion implantation, required for device fabrication, introduces defects that often kill the carrier lifetime and limit the device operations. Thus, extensive research is necessary to understand the defects created during ion implantation.

Photoluminescence (PL) Spectroscopy captures light produced from a substance bombarded with a laser beam. The PL spectrum frequently displays spectral peaks associated with defects present in the host material. This technique's great sensitivity allows it to detect extremely low quantities of deliberate and accidental contaminants that can have a significant impact on material quality and device performance. In the present work, the luminescence induced by unique energy-loss mechanisms of 100 MeV Ag swift heavy ions, and 25 keV He low energy light ions in single crystals of semi-insulating 4H-SiC is investigated and compared using photoluminescence spectroscopy. Before the experiment, the simulation of the concentration of vacancy defects with depth is carried out using Monte-Carlo based TRIM simulation code [6] to estimate various irradiation fluences (ions/cm²) and the corresponding displacements per atoms (dpa, 1 dpa means that all atoms are displaced at least once from their respective lattice sites). Experimental results (Fig. 1) show strong evidence of V_Si emitters and emissions from two commonly observed unknown defects (UD₃ and UD₄) in 4H-SiC after both irradiations. The silicon-vacancy is a trapping centre, which is important in SiC metal-oxide-semiconductor technology [7].  Besides, V_Si is a promising single-photon emitter exhibiting millisecond spin coherence [8]. Most of the conclusions drawn from the results on the ion irradiation of SiC opens up new problems and perspectives.

Fig.1. Low-temperature photoluminescence (∼77 K) spectra were recorded using a 266 nm deep UV excitation before and after (a) 100 MeV Ag irradiation, and (b) 25 keV He ion irradiation in semi-insulating 4H-SiC with various indicated fluences (ions/cm²). Recording range: 850–1150 nm.

References

[1] M. Schupbach, M, The Next-generation of Sic-based Power Systems, (2007).

[2] Stefano Lovati,  10 Things To know About SiC, March 2021

https://www.powerelectronicsnews.com/10-things-to-know-about-sic/

[3] M. D. Paolo Emilio, Silicon Carbide for the Success of Electric Vehicles, August 2020

https://www.powerelectronicsnews.com/silicon-carbide-for-the-success-of-electric-vehicles/

[4] Stefania Castelletto and Alberto Boretti, J. Phys. Photonics 2, 022001 (2020).

https://doi.org/10.1088/2515-7647/ab77a2

[5]Michael Rueb, A novel ion-implantation technique improves the manufacture of SiC power devices, including super-junction MOSFETs, Compound Semiconductor, Volume 25 Issue 3, April/May 2019.

https://publishing.ninja/V4/page/9077/377/6/

[6] J. F. Ziegler, M. D. Ziegler, and J. P. Biersack, Nucl. Instrum. Methods Phys. Res. Sect. B 268, 1818 (2010).

 https://doi.org/10.1016/j.nimb.2010.02.091

[7] C. J. Cochrane, Applied Physics Letters 100, 023509 (2012).

https://doi.org/10.1063/1.3675857

[8] M. E. Bathen et. al., npj Quantum Information 5, Article number: 111 (2019).

https://doi.org/10.1038/s41534-019-0227-y