VIII.2. A Semiconductor Device Primer

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The Si diode shows a “textbook” exponential forward characteristic at currents >10 nA, whereas the Ge diode exhibits a more complex structure. A “state-of-the-art” reverse diode characteristic (Steve Holland) Reverse Bias Current [pA] 50 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 100 Reverse Bias Voltage [V] The depletion width is 300 μm, attained at about 20 V. The area of the diode is 9 mm 2 , so the reverse leakage current of 40 pA corresponds to 450 pA/cm 2 , which is about 10x the theoretical value. Introduction to Radiation Detectors and Electronics Copyright © 1998 by Helmuth Spieler VIII.2.a. A Semiconductor Device Primer, Doping and Diodes
The discrepancies between the measured results and the simple theory require the analysis of additional processes in the depletion zone. One can recognize four regions in the forward current: a) generation- recombination in the depletion region b) diffusion current (as just calculated for the ideal diode) c) high-injection region where the injected carrier concentration affects the potentials in the neutral regions. d) voltage drop due to bulk series resistance The reverse current is increased due to generation currents in the depletion zone. Introduction to Radiation Detectors and Electronics Copyright © 1998 by Helmuth Spieler VIII.2.a. A Semiconductor Device Primer, Doping and Diodes
Page 1 and 2: VIII.2. A Semiconductor Device Prim
Page 3 and 4: The number of occupied electron sta
Page 5 and 6: With these simplifications the numb
Page 7 and 8: 2. Carrier Concentrations in Doped
Page 9 and 10: It is often convenient to refer all
Page 11 and 12: Equilibrium is attained when the tw
Page 13 and 14: As either NA or ND increases relati
Page 15 and 16: 4. The Forward-Biased p-n Junction
Page 17 and 18: This yields the solution n p ( x) =
Page 19 and 20: Since the two electron currents mus
Page 21 and 22: Energy band diagrams showing the in
Page 23 and 24: Since the equilibrium concentration
Page 25 and 26: Note that in the diode equation a)
Page 27: However, on a logarithmic scale it

VIII.2. A Semiconductor Device Primer

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