半導體量測技術 Semiconductor Materials and Device Characterization Topic 6: charge pumping technique and HS experiment Instructor: Dr. YiMu Lee Department of Electronic Engineering National United University. Topics: Ch. 6 in D. K. Schroder. Charge pumping method (p. 379)
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Semiconductor Materials and Device Characterization
Topic 6: charge pumping technique and HS experiment
Instructor: Dr. YiMu Lee
Department of Electronic Engineering
National United University
01/05 = 5 students
1951, Bell Labs
independent measurement of minority carrier mobility () and diffusion coefficient (D)
basic principles
 field applied to semiconductor bar
narrow pulse, high concentration of minority carriers generated
pulse drifts due to
(time to drift a fixed distance mobility
pulse spreads due to diffusion ( diffusion coefficient)
In Fig. 418 (ntype material n0 >> p0)
pulse of holes generated at t=0


pulse of holes drift indirection
pulse monitored at x = L; drift velocity Vd is
consider diffusion without drift or recombination
Eq (13b) or (433b) (p. 418):
pulse width = full width @ 1/e pts.
for a fixed peak height
, the pulse width x can be found
(21)(445)
where td is the time corresponding to the pulse spread x
(21)
, or
(22)(446)
Example 46 ntype Ge is used in a HaynesSchockley experiment. The length of the Ge bar is 1 cm, the probes are spaced 0.95 cm apart.
battery voltage is 2.0 V
td = 0.25 ms
pulse width t (oscilloscope) = 117 s
Find p and Dp (and check agreement w/ the Einstein relations