Carbon vacancy control in p⁺-n silicon carbide diodes for high voltage bipolar applications

Abstract

Controlling the carbon vacancy (V C ) in silicon carbide (SiC) is one of the major remaining bottleneck in manufacturing of high voltage SiC bipolar devices, because V C provokes recombination levels in the bandgap, offensively reducing the charge carrier lifetime. In literature, prominent V C evolutions have been measured by capacitance spectroscopy employing Schottky diodes, however the trade-offs occurring in the p + -n diodes received much less attention. In the present work, applying similar methodology, we showed that V C is re-generated to its unacceptably high equilibrium level at ∼2×10 13 V C /cm 3 by 1800 • C anneals required for the implanted acceptor activation in the p + -n components. Nevertheless, we have also demonstrated that the V C eliminating by thermodynamic equilibrium anneals at 1500 • C employing carbon-cap can be readily integrated into the p + -n components fabrication resulting in ≤10 11 V C /cm 3 , potentially paving the way towards the realization of the high voltage SiC bipolar devices.

The effects of different anode manufacturing methods on deep levels in 4H-SiC p+n diodes

“…Previous studies have shown that [V C ] reduction can be achieved by C i injection from a C-cap, even a lower annealing temperatures. 34,35 It was reported that tensile strain can lead to a shift to lower temperature of B-related DLTS peak, 36 which is not observed in our case. This means that the present results might support the second hypothesis.…”

Correlations between reverse bias leakage current, cathodoluminescence intensity and carbon vacancy observed in 4H-SiC junction barrier Schottky diode

“…For example, V C is commonly found in 4H-SiC epi materials. It can be thermally generated during the high temperature fabrication process, such as the annealing activation of the Al p-type dopant after the Alion implantation [12]. The presence of V C would degrade the device performance, such as decreasing the minority carrier lifetime [7][8][9] and increasing the reverse bias leakage current of the JBS diode [11].…”

“…Al-ion implantation followed by hightemperature annealing is crucial to introduce p-type doping in 4H-SiC bipolar device fabrication [5]. Carbon vacancy was created in the ion-implantation and subsequent high temperature annealing [12]. It is thus important to have a probe capable of characterizing carbon vacancy in the line of the SiC device fabrication.…”

Dynamic reactions of defects in ion-implanted 4H-SiC upon high temperature annealing

“…In particular, defects in 4H-SiC can be engineered through external electron irradiation or ion implantation, which have been demonstrated as a promising strategy to develop single-photon emitters (SPEs) as quantum building blocks. For instance, the induced defects and their complexes include silicon-vacancy (V Si ) [3], nitrogen-vacancy (N C -V Si ) [4], carbon antisite-vacancy pair (C Si -V C ) [5], divacancy (V Si -V C ) [6], and so on, which have been utilized as SPEs and qubit systems, while the carbon-vacancy (V C ) [11,12] with a low formation energy (<5 eV) is known as the prime carrier lifetime killer in SiC devices [13,14], which has the harmful quenching effect on the developed single-photon.…”