List of Figures
Figure 1.1 - Standard step recovery diode pulse sharpening circuits.
Figure 2.1 - Reverse recovery test circuit
Figure 2.2a - Ideal reverse recovery transients for a step recovery diode.
Figure 2.2b - Ideal reverse recovery transients for a power rectifier.
Figure 2.3 - Typical epitaxial diode structure
Figure 2.4 - Typical diffused diode structure
Figure 2.5 - pin doping structure and carrier densities
Figure 2.6 - Charge Removal in the i-Layer.
Figure 2.7 - Schematic illustration of carrier removal [Benda67]
Figure 2.8 - Reverse voltage development in a pspn rectifier.
Figure 2.9 - Reverse voltage development in a psnn rectifier.
Figure 2.10 - Carrier density and net charge evolution in an SRD [Roul90]
Figure 2.11 - A comparison of ramp voltage VRAMP and corresponding breakdown voltages for punchthrough and non-punchthrough pin structures.
Figure 3.1 - Step Recovery Test Circuit
Figure 3.2 - Output of pulse generator (158 V/div, 5 ns/div)
Figure 3.3 - Output pulse when sharpened with diode 13. (158 V/div, 5ns/div)
Figure 3.4 - Doping profile of diode 13. Note the very wide epitaxial layer, bounded by a highly doped substrate.
Figure 3.5 - Output pulse when sharpened with diode 103. (158 V/div, 5ns/div)
Figure 3.6 - Doping profile of diode 103. Note the moderately wide epitaxial layer, bounded by a highly doped substrate.
Figure 3.7 - Output pulse when sharpened with diode 100. (158 V/div, 5ns/div)
Figure 3.8 - Doping profile of diode 100. Note the moderately wide epitaxial layer, bounded by a highly doped substrate.
Figure 3.9 - Output pulse when sharpened with diode 47. (158 V/div, 5ns/div). Note the SRD-like pulse sharpening.
Figure 3.10 - Doping profile of diode 47. Note the diffused profile.
Figure 3.11 - Output pulse when sharpened with diode 89. (158 V/div, 5ns/div). Note the SRD-like pulse sharpening.
Figure 3.12 - Doping profile of diode 89. Note the diffused profile.
Figure 3.13 - Output pulse when sharpened with diode 88. (158 V/div, 5ns/div). Note the SRD-like pulse sharpening.
Figure 3.14 - Doping profile of diode 88. Note the diffused profile.
Figure 4.1. Doping profile of the devices considered in this chapter.
Figure 4.2 The breakdown voltage contours (labeled in Volts) calculated using EC = 225 kV/cm.
Figure 4.3. The breakdown voltage contours (labeled in Volts) calculated using the Medici device simulator.
Figure 4.4. The relative difference between the breakdown voltages presented in Figure 4.2 and the Medici simulations in Figure 4.3.
Figure 4.5. The critical electric field, EC(λ,L), contours (labeled in kV/cm) as determined from the Medici simulations.
Figure 4.6. The relative difference between the breakdown voltages calculated using the EC(λ,L) given in equation (4.10) and Medici simulations.
Figure 4.7. The doping gradient at the junction.
Figure 4.8. Doping and field profiles for λ = 25 μm, L = 35 μm.
Figure 4.9. Doping and field profiles for λ = 25 μm, L = 125 μm.
Figure 4.10. Doping and field profiles for λ = 25 μm, L = 200 μm.
Figure 4.11. Doping and field profiles for λ = 25 μm, L = 250 μm.
Figure 4.12. Doping and field profiles for L = 200 μm, λ = 10 μm.
Figure 4.13. Doping and field profiles for L = 200 μm, λ= 20 μm.
Figure 5.1 - Doping Profile of EP1
Figure 5.2 - Doping Profile of DF1
Figure 5.3 - The transient response of EP1. The labeled data points correspond to the individual curves in Figure 5.5.
Figure 5.4 - The transient response of DF1. The labeled data points correspond to the individual curves in Figure 5.6.
Figure 5.5 - Electric field evolution in EP1. The curve labels correspond to the individual time points shown in Figure 5.3.
Figure 5.6 - Electric field evolution in DF1. The curve labels correspond to the individual time points shown in Figure 5.4. (Curves A and B are too small to appear at the scale used.)
Figure 5.7 - Transient response of DF2. The labeled data points correspond to the individual curves in Figure 5.8 and 5.17.
Figure 5.8 - Net charge evolution in DF2. The curve labels correspond to the individual time points shown in Figure 5.7. (Curves A and B are too small to appear at the scale used.) The arrow shows the "charge wave" nature of the charge evolution with time.
Figure 5.9 - Transient response of DF3. The labeled data points correspond to the individual curves in Figure 5.10.
Figure 5.10 - Net charge evolution in DF3. The curve labels correspond to the individual time points shown in Figure 5.9. (Curves A, B and C are too small to appear at the scale used.)
Figure 5.11 - Transient response of DF4. The labeled data points correspond to the individual curves in Figure 5.12.
Figure 5.12 - Net charge evolution in DF4. The curve labels correspond to the individual time points shown in Figure 5.11. (Curves A and B are too small to appear at the scale used.)
Figure 5.13 - Transient response of DF5. The labeled data points correspond to the individual curves in Figure 5.14 and 5.18.
Figure 5.14 - Net charge evolution in DF5. The curve labels correspond to the individual time points shown in Figure 5.13. (Curves A and B are too small to appear at the scale used.) The left arrow shows the "charge collapse" nature of the charge evolution with time. The right arrow shows the later development of the second space charge region.
Figure 5.15 - Transient response of DF6. The labeled data points correspond to the individual curves in Figure 5.16.
Figure 5.16 - Net charge evolution in DF6. The curve labels correspond to the individual time points shown in Figure 5.15. (Curves A and B are too small to appear at the scale used.)
Figure 5.17 - Electric field evolution in DF2. The curve labels correspond to the individual time points shown in Figure 5.7. (Curves A and B are too small to appear at the scale used.)
Figure 5.18 - Electric field evolution in DF5. The curve labels correspond to the individual time points shown in Figure 5.13. (Curves A and B are too small to appear at the scale used.)
Figure 5.19 - A typical SRD pulse-sharpening waveform.
Figure 5.20 - Typical screen shot from WFSRD parameter calculation program. 89Figure 5.21 - WFSRD parameter calculation program output for the device to be fabricated.
Figure 5.22 - Dimensional and switching parameters for the fastest WFSRD devices with the indicated breakdown voltage.
Figure 5.23 - Dimensional and switching parameters for devices that are 33% slower than the fastest WFSRD devices with the indicated breakdown voltage.
Figure 6.1 - Doping profile as a function of drive-in time.
Figure 7.1 - Reverse I-V characteristic for A8.6. Scale: 100 V/div horizontally, 50 μA/div vertically. The origin is at the upper-right corner.
Figure 7.2 - Forward I-V curve for A8.6. Scale: 1 V/div horizontally, 10 mA/div vertically. The origin is at the lower-left corner. 103Figure 7.3 - Series-connected pulse sharpening test circuit.
Figure 7.4 - Output of the circuit of Figure 7.3 for A8.6 with IBIAS = 2,4,6,8,10, and 12 mA. The widest pulse is the input waveform. (Actual output scale: 50 mV/div 70 dB = 158 V/div, and 5 ns/div).
Figure 7.5 - Output of the circuit of Figure 7.3 for A8.6 with IBIAS = 6,12,18,24, and 30 mA. The widest pulse is the input waveform. (Actual output scale: 50 mV/div 70 dB = 158 V/div, and 5 ns/div).
Figure 7.6 - Output of the circuit of Figure 7.3 for A8.PT.850.1 with IBIAS = 20, 40, 60, 80, 100, 120, 140, 160, 180, and 200 mA. The widest pulse is the input waveform. (Actual output scale: 50 mV/div 70 dB = 158 V/div, and 5 ns/div).
Figure 7.7 - Fast input shunt-connected pulse sharpening test circuit.
Figure 7.8 - Output of the circuit of Figure 7.7 with diode A8.6 for IBIAS = 0, 2, 4, 6 and 8 mA. The earliest pulse is the input waveform. (Actual output scale: 50 mV/div 70 dB = 158 V/div, and 2 ns/div)
Figure 7.9 - Slower input shunt-connected pulse sharpening test circuit
Figure 7.10 - Output of Figure 7.9 with diode A8.6 for IBIAS = 0, 6, 12 and 18 mA. The slowest pulse is the input waveform. (Actual output scale: 20 mV/div 70 dB = 63 V/div, and 10 ns/div)
Figure 7.11 - Output of the circuit of Figure 7.7 with diode A8.PT.850.1 for IBIAS = 0, 15, 30, 45 and 60 mA. The widest pulse is the input waveform. (Actual output scale: 50 mV/div 70 dB = 158 V/div, and 1 ns/div)
Figure 8.1. Calculated charge injection in a pin diode during the forward transient, for several different values of t/τ. The horizontal axis is linear, and the vertical axis is logarithmic. Note that substantial charge injection occurs at both junctions throughout the entire transient. pSS(X) is the steady-state distribution.
Figure 8.2. Diffusion current as a fraction of the total current, at both junctions. In the limiting case of no middle-layer doping, f = 0 and the diffusion and drift components are equal. For very heavy doping, f → ∞ and the high-low junction current is almost entirely drift current, and the p+n junction current is almost entirely diffusion current.
Figure 8.3. Simulations calculated using the MEDICI simulator to confirm the validity of the derived expression for J0. J0 is calculated from (8.31). For JF/J0 > 10, the diode behaves like a pin diode, with substantial charge injection at both junctions. For JF/J0 < 0.1, charge injection occurs exclusively at the p+n- junction. JF = J0 is an intermediate case. In each case JF = 10 A/cm2, and ND is varied to change J0. In order of decreasing JF/J0 the corresponding values of ND are 2.6x1012, 1.2x1013, 5.6x1013, 2.6x1014, and 1.2x1015 cm-3.
Figure 8.4. Simulations calculated using the MEDICI simulator. The injected hole density at the high-low junction at t = tdi is shown for several different dopings. In each case, the peak density >> ND. The charge injected at the high-low junction grows rapidly after t = tdi, due to the onset of double injection.
Figure 8.5. The curves on this design chart show the maximum practical storage time tS, in nanoseconds, for a psn diode with a middle-layer width factor WF of 1, 1.65, 2, or 3, and breakdown voltage VBR (in Volts).
Figure 8.6. Maximum practical storage time tS, and the corresponding forward bias time tF, in nanoseconds, for a psn diode with the ideal middle-layer width factor WF of 1 and breakdown voltage VBR (in Volts).
Figure 8.7 - Optimum pulse sharpening action of the 4000 V device described in Table 8.1. The sharpened output 10%-90% rise time is 7.8 ns.
Figure 8.8 - Simulation results for the diode and circuit conditions in [Grek85].
Figure 9.1 - Possible heterostructure SRD, using Si-Ge alloys.
Figure A.1 - Diode model used for measuring C-V profiles in reverse bias. The current source represents the DC leakage current, and the capacitor models the diode junction capacitance.
Figure A.2 - Schematic diagram of the high-voltage C-V profiler circuit. The output voltage VR is directly proportional to the capacitance of the diode under test (DUT).
Figure B.1. Schematic diagram of the pulse amplifier. The first Class D stage shapes a fast pulse to trigger the second Class D stage. Both stages are buffered by complementary emitter-followers to ease the drive requirements.
Figure B.2. Typical output waveform for the circuit of Figure B.1. Scale: 10 V/div, 10 ns/div.
Figure B.3. Test circuit for reverse recovery transient measurements. The diode conducts a reverse current for a short time.
Figure B.4. Reverse recovery transient for a 1N4148 diode. The 1N4148 is a fast switching diode, as demonstrated by its very short reverse recovery transient. Scale: 10 V/div, 10 ns/div.
Figure B.5. Reverse recovery transient for a TRW DSR3400X fast-recovery rectifier. Note the undesirable "snappy" response. Scale: 10 V/div, 10 ns/div.
Figure B.6. Reverse recovery transient for a Central Semiconductor 1N4936 fast-recovery rectifier. Note the classic textbook form of the reverse recovery transient. Scale: 10 V/div, 20 ns/div.
Figure B.7. Doping profile of the TRW DSR3400X fast-recovery rectifier. The doping profile is clearly diffused, as suggested by the snappy reverse recovery transient.
Figure B.8. Doping profile of the Central Semiconductor 1N4936 fast-recovery rectifier. The doping profile shows an active region consisting of an nearly intrinsic layer followed by a lightly doped layer. This modern design produces the smooth transient shown in Figure B.6, rather than an abrupt transient like that shown in Figure B.7.
Figure B.9. Reverse transient for the M/A-Com MA44952 step recovery diode. This data allows the effective lifetime to be calculated.
Figure C.1 - Depletion region width as a function of EC. The 4000/EC curve shows that WDR decreases proportionately faster than EC increases. EC is in V/cm, W is in cm.
Figure D.1 - Variation of simulated switching time with lifetime, for equal stored charge, with the structure described in Section 5.6 and the circuit described in Section 7.3.
