Reversal of forward voltage drift in 4H-SiC p-i-n diodes via low temperature annealing

Abstract

Recent reports have shown that Shockley stacking fault (SSF) growth in 4H-SiC may be reversed via low temperature (210–600°C) annealing. It is not clear if the associated drift in the forward voltage drop (Vf) is also reversed. Here we show that annealing of SSFs causes the complete and repeatable recovery of Vf. Furthermore, by looking at the time-dependent recovery of Vf during both the current stressing and thermal annealing of a single diode, we ascertain that the mechanisms for these two processes are different.

Influence of Temperature on Shockley Stacking Fault Expansion and Contraction in SiC PiN Diodes

“…First of all, as reported previously by Caldwell et al 13,14 and Miyanagi et al 15 it should be reiterated that not only can SSFs expand, but due to low-temperature (400°C to 700°C) annealing, the SSFs have been shown to contract, which is associated with a complete and repeatable recovery of the V f drift as well. 14 Here, the time constants for this recovery as a function of temperature were reported and an activation energy of 1.3 ± 0.3 eV was determined.…”

“…[13][14][15]19 However, direct comparisons between the activation energy we report for the annealing process with those currently discussed in the literature 16,17 are not straightforward. Previous measurements involved determining the distance a given partial dislocation propagated due to mechanical stress, in the absence of injected electron-hole pairs (EHPs) 16 or due to the optical injection of EHPs via above band gap light, 17 which provided activation energies of 2.5 and 0.25 eV, respectively.…”

“…At the same time they proposed a third model stating that the 3C-SiC structure of the SSF, not the native 4H-SiC lattice, was the thermodynamically favorable polytype and therefore the formation was driven by the improved thermodynamic stability of the 3C-SiC. This latter model was also disproved, in this case by the experiments of Caldwell et al 13,14 and Miyanagi et al, 15 where they showed that SSFs created and expanded within PiN diodes and n -epitaxial layers, respectively, could be contracted back to the original BPDs from which they were nucleated via lowtemperature (400°C to 700°C) annealing. Therefore, this leaves only the initial model described by Lambrecht and Miao 7 and Miao et al 8 to be explored further.…”

“…Following the experiments of Caldwell et al 13 and Miyanagi et al, 15 Caldwell et al 14 later reported that through the aforementioned annealing of pin diodes, not only were the SSFs observed to contract, but also a complete and repeatable recovery of the V f drift occurred. Here, we report on measurements providing the activation energy of the V f drift recovery that occurs due to low-temperature (500°C to 700°C) annealing-induced SSF contraction.…”

Low-loss, infrared and terahertz nanophotonics using surface phonon polaritons

“…However, such defects may also act as nanometer-scale sources of modified SPhP response that can be useful in the design of patterned nanophotonic or metamaterial devices. For instance, the incorporation of stacking faults in silicon carbide [69,70,[163][164][165][166][167][168][169][170][171][172][173] could provide a means to modify the Reststrahlen band and, therefore, the SPhP response of specific nanostructures or nanophotonic/metamaterial designs. Experimental evidence for this were reported by Ocelic et al [162] where it was demonstrated that the SPhP response could be severely damped via the patterned implantation of Be 3+ ions into a SiC surface using ion beam implantation.…”