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106
CHAPTER 7. DIODES
Temperature dependence
The temperature affects many of the parameters in the equations above, the following equations show how. One of the most significant parameter that varies with the temperature for a
semiconductor is the band-gap energy:
EGnom = 1.16 − 7.02e−4 ·
TNOM2
TNOM + 1108.0
(7.6)
EG(T ) = 1.16 − 7.02e−4 ·
T2
TNOM + 1108.0
(7.7)
The leakage currents temperature dependence is:
IS(T ) = IS · e
log f actor
N
JSW (T ) = JSW · e
log f actor
N
(7.8)
(7.9)
where "logfactor" is defined:
log f actor =
EG
T
EG
−
+ XTI · ln(
)
Vt (TNOM) Vt (T )
TNOM
(7.10)
The contact potentials (bottom-wall an sidewall) temperature dependence is:
T
T
EGnom
EG(T)
V J(T ) = VJ · (
) −Vt (T ) · 3 · ln(
)+
−
TNOM
TNOM
Vt (TNOM) Vt (T )
T
T
EGnom
EG(T)
PHP(T ) = PHP · (
) −Vt (T ) · 3 · ln(
)+
−
TNOM
TNOM
Vt (TNOM) Vt (T )
(7.11)
(7.12)
The depletion capacitances temperature dependence is:
V J(T )
−4
CJ(T ) = CJ · 1 + MJ · (4.0e · (T − TNOM) −
+ 1)
VJ
PHP(T )
−4
CJSW (T ) = CJSW · 1 + MJSW · (4.0e · (T − TNOM) −
+ 1)
PHP
(7.13)
(7.14)
The transit time temperature dependence is:
T T (T ) = TT · (1 + TTT1 · (T − TNOM) + TTT2 · (T − TNOM)2 )
(7.15)
The junction grading coefficient temperature dependence is:
MJ(T ) = MJ · (1 + TM1 · (T − TNOM) + TM2 · (T − TNOM)2 )
(7.16)
The series resistance temperature dependence is:
RS(T ) = RS · (1 + TRS · (T − TNOM) + TRS2 · (T − TNOM)2 )
(7.17)