Terahertz Radiators Based on Silicon Carbide Avalanche Transit …
29
zero. The changes of peak electric field (ξ p ), breakdown voltage (V B ), avalanche zone
voltage (V A ), and avalanche layer width (x A ) of Si, 3C-SiC, and type-IIb diamond
DDR IMPATTs versus operating frequency plots are shown in Figs. 6, 7 and 8,
respectively. It is observed that ξ p increases while V B , V A , and x A decrease with
operating frequency. It can be observed from Figs. 6 and 7 that the peak electric
fields are minimum in 3C-SiC IMPATTs, while the breakdown voltages of those
are largest among all. However, the IMPATT diodes based on 3C-SiC possess much
broader avalanche zone beyond 140 GHz which indicates greater noise level of
3C-SiC-based source.
Significant large-signal parameters like optimum frequency (f p ), avalanche resonance frequency (f a ), peak negative conductance (G p ), susceptance (B p ), power
output (P RF ), and efficiency (η L ) are acquired from large-signal simulation. The G p
and B p versus f p are illustrated in Figs. 9a, b, respectively. Highest magnitudes of G p
in 3C-SiC-based IMPATTs indicate the higher power delivery capability of those as
compared to diamond and Si IMPATTs, which is reflected in Fig. 10a. At 94 GHz,
diamond IMPATT delivers highest RF power. But the frequencies above 140 GHz,
3C-SiC-based IMPATTs are more suitable for the production of RF output power as
per graph plotted in Fig. 10a. However, the DC to RF conversion efficiency of 3C-SiC
IMPATTs is observed to be significantly low (much lower than the diamond and Si
IMPATTs) due to their large bias current requirements. The bias current density (J 0 ),
f p , f a and junction diameter (D j ) of the diodes are shown in Table 2.
Fig. 6 Variations of peak electric field at metallurgical junction of Si, 3C-SiC, and type-IIb
diamond-based IMPATT diodes with operating frequency
29
zero. The changes of peak electric field (ξ p ), breakdown voltage (V B ), avalanche zone
voltage (V A ), and avalanche layer width (x A ) of Si, 3C-SiC, and type-IIb diamond
DDR IMPATTs versus operating frequency plots are shown in Figs. 6, 7 and 8,
respectively. It is observed that ξ p increases while V B , V A , and x A decrease with
operating frequency. It can be observed from Figs. 6 and 7 that the peak electric
fields are minimum in 3C-SiC IMPATTs, while the breakdown voltages of those
are largest among all. However, the IMPATT diodes based on 3C-SiC possess much
broader avalanche zone beyond 140 GHz which indicates greater noise level of
3C-SiC-based source.
Significant large-signal parameters like optimum frequency (f p ), avalanche resonance frequency (f a ), peak negative conductance (G p ), susceptance (B p ), power
output (P RF ), and efficiency (η L ) are acquired from large-signal simulation. The G p
and B p versus f p are illustrated in Figs. 9a, b, respectively. Highest magnitudes of G p
in 3C-SiC-based IMPATTs indicate the higher power delivery capability of those as
compared to diamond and Si IMPATTs, which is reflected in Fig. 10a. At 94 GHz,
diamond IMPATT delivers highest RF power. But the frequencies above 140 GHz,
3C-SiC-based IMPATTs are more suitable for the production of RF output power as
per graph plotted in Fig. 10a. However, the DC to RF conversion efficiency of 3C-SiC
IMPATTs is observed to be significantly low (much lower than the diamond and Si
IMPATTs) due to their large bias current requirements. The bias current density (J 0 ),
f p , f a and junction diameter (D j ) of the diodes are shown in Table 2.
Fig. 6 Variations of peak electric field at metallurgical junction of Si, 3C-SiC, and type-IIb
diamond-based IMPATT diodes with operating frequency