Potentiality of Impact Avalanche Transit Time Diode …
69
=
τ A
2J s α A
⎛
⎝ 1 −
W
0
αdx
⎞
⎠
=
τ A
2J s
∂α
∂ E
A
⎛
⎝ 1 −
W
0
αdx
⎞
⎠
(6)
C A =
ε s A
X A
(7)
and the resonant frequency of this L-C combination is given by
ω r = 2π f r =
2α v s J 0
ε s
(8)
where J 0 is the DC current density, α
= (∂α/∂ E), A and α are diode area and
ionization integrand, respectively [7]. Drift response time is given by
τ D =
(W − X A )
v s
(9)
and the drift capacitance is
C Drift =
Aε s
(W − X A )
(10)
Recently reported design parameters have been used in our numerical study [17].
3 Results and Discussion
The frequency, where maximum efficiency is obtained, is termed here as peak frequency. IMPATT’s efficiencies by using different materials are given in Table 1. The
highest efficiency of 14.12% is obtained from InP at 20 THz, which is the maximum
among all. InP has better efficiency at all corresponding frequencies. GaAs has the
closest value to InP. Si and Ge have moderate level, whereas WzGaN has very low
efficiency. Peak frequencies for GaAs, Si, Ge and WzGaN are 20 THz, 20 THz,
22 THz and 22 THz, respectively.
69
=
τ A
2J s α A
⎛
⎝ 1 −
W
0
αdx
⎞
⎠
=
τ A
2J s
∂α
∂ E
A
⎛
⎝ 1 −
W
0
αdx
⎞
⎠
(6)
C A =
ε s A
X A
(7)
and the resonant frequency of this L-C combination is given by
ω r = 2π f r =
2α v s J 0
ε s
(8)
where J 0 is the DC current density, α
= (∂α/∂ E), A and α are diode area and
ionization integrand, respectively [7]. Drift response time is given by
τ D =
(W − X A )
v s
(9)
and the drift capacitance is
C Drift =
Aε s
(W − X A )
(10)
Recently reported design parameters have been used in our numerical study [17].
3 Results and Discussion
The frequency, where maximum efficiency is obtained, is termed here as peak frequency. IMPATT’s efficiencies by using different materials are given in Table 1. The
highest efficiency of 14.12% is obtained from InP at 20 THz, which is the maximum
among all. InP has better efficiency at all corresponding frequencies. GaAs has the
closest value to InP. Si and Ge have moderate level, whereas WzGaN has very low
efficiency. Peak frequencies for GaAs, Si, Ge and WzGaN are 20 THz, 20 THz,
22 THz and 22 THz, respectively.