Managing Basal Plane Dislocations in SiC: Perspective and Prospects

Abstract

Conversion of basal plane dislocations (BPDs) to threading edge dislocations in 8 and 4° offcut SiC material has been studied in order to eliminate the nucleation source of Shockley-type stacking faults in the active region of bipolar devices. Ex situ and in situ growth interrupts were used to convert BPDs in the 8° material, where conversion rates up to 98% were achieved for in situ interrupts in epilayers with doping < 1x10 16 cm -3 . Complete spontaneous conversion of BPDs was found to be possible in 4° offcut material after ~ 20 µm of epitaxial growth for both intentionally and unintentionally doped films.

Challenges of Overcoming Defects in Wide Bandgap Semiconductor Power Electronics

“…In a bipolar power semiconductor switching device (Figure 1a), the high-level injection of minority carriers is required to achieve significant conductivity modulation and reduce the on-state resistance. If the semiconductor contains a high density of crystal defects, as is the case with wide bandgap (WBG) semiconductors, minority carrier recombination is adversely affected [21,22]. The basal plane dislocations (BPDs) present in SiC are excited by the energy released from the minority carrier recombination process, which leads to additional BPD generation along with its associated movement within the semiconductor material, causing an increase in the on-state resistance and eventual thermal run-away in a forward biased bipolar junction diode.…”

(Invited) Crystal Defects in Wide Bandgap Semiconductors

“…For example, it has been shown more than a decade ago [21,22] that basal plane dislocations (BPDs) present in SiC are excited by the energy released from minority carrier recombination process; the result is excess BPD generation and its glide within the semiconductor material that leads to an increase in the drift-region resistance and thermal run-away in a forward biased bipolar junction diode. This finding prompted the worldwide research community to investigate new material synthesis techniques that convert BPDs into threading edge dislocations (TEDs) [23,24]; however, to date the exact role of TEDs on device performance and reliability, especially under extreme environments is not known. In a similar development, the space-charge injected during voltage switching in a majority carrier device such as the Schottky barrier diode (Figure 7(b)), has been shown to be detrimental as it leads to "hot spots" and failures in SiC at a moderately low dv/dt value (Figure 8(a)) [25].…”

On the Power-Handling Capability of Wide Bandgap (WBG) Semiconductor Power Switching Devices

“…For example, it has been shown more than a decade ago [6,7] that basal plane dislocations (BPDs) present in SiC are excited by the energy released from minority carrier recombination process; the result is excess BPD generation and its glide within the semiconductor material that leads to an increase in the drift-region resistance and eventual thermal run-away in a forward biased bipolar junction diode. This finding prompted the world-wide research community to investigate new material synthesis techniques that convert BPDs into threading edge dislocations (TEDs) [8,9]; however, to date the exact role of TEDs on device performance and reliability, especially under extreme environments is not known. In a similar development, the space-charge injected during voltage switching in a majority carrier device such as the Schottky barrier diode (Figure 2(b)), has been shown to be detrimental as it leads to "hot spots" and failures in SiC at a moderately low dv/dt value (Figure 2(a)) [10].…”