4.4.2.1 PiN Diode Structure

Fig. 4.9 shows the cross section of a high-voltage PiN diode in SiC [176].

Figure 4.9: Cross section of high voltage PiN diode in SiC.

The p+ anode is formed during epitaxial growth, and selectively removed using reactive ion etching (RIE). A p-type JTE ring is implanted, and ohmic contacts are established to the anode and the substrate. P-type ohmic contacts are typically pure Al or Al/Ti alloys, n-type ohmic contacts are made of Ni. Contacts are annealed at 850$~^{\circ}$C-1000$~^{\circ}$C, forming an Al-rich p+ surface layer in the case of p-type contacts or a Ni silicide layer in the case of n-type contacts. Optimized device parameters used in the simulation are listed in Table 4.2.

Table 4.2: Summary of optimized device parameters used for the simulation of a PiN diode.

parameter	value
p+ thickness and concentration	$0.5\,\mathrm{\mu}$m, $1.0\times 10^{17}$ cm$^{-3}$
n$-$ epilayer thickness and concentration	$10.5\,\mathrm{\mu}$m, 7.2 $\times10^{15}$ cm $^{-3}$
n+ cathode thickness and concentration	$1.0\,\mathrm{\mu}$m, $1.0\times10^{19}$ cm$^{-3}$

T. Ayalew: SiC Semiconductor Devices Technology, Modeling, and Simulation