The forward biased I-V characteristics of real p-n diodes are affected by generation-recombination mechanisms in the...

  

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The forward biased I-V characteristics of real p-n diodes are affected by generation-recombination mechanisms in the depletion region, by the high injection and the series resistance of the diode. The I-V characteristics of a prototypical diode are plotted on a semi-logarithmic scale and four different regions can be distinguished as indicated on the figure below. 1.E+03 Current Density (A/cm²) 1E+01 1E-01 1E-03 1.E-05 1.E-07 1E-09 Depletion region recombinanon 0 Ideal chode (b) T₁=T=0.1μs P 0.3 High Injection 0.6 1 = 1, exp P() 77=2 Senes Resistance 0.9 Voltage (V) From the results presented in this figure it is evident that there is the ideal diode region where the current increases by one order of magnitude as the voltage is increased by 60 mV. This region is referred to as having an ideality factor, n, of one. The ideality factor is obtained by fitting a section of the curve to the following expression for the current: 1.2 Looking at the slope of the curve, to the left of the ideal diode region there is the region where the current is dominated by the trap-assisted recombination in the depletion region. This part of the curve has an ideality factor of two. To the right of the ideal diode region, the current becomes limited by high injection effects and by the series resistance. The above behavior can be simulated using PN Junction Lab at www.nanohub.org that is part of the ABACUS tool-based curricula https://nanohub.org/resources/abacus. You can directly access the pn- junction lab tool using the following link: https://nanohub.org/tools/pntoy. Hence, the purpose of this exercise is to examine how pronounced are each of the four regions for a diode with NA-10¹6 cm ³ and No=10¹5 cm ³. Sweep the anode voltage from VA=0V to V₁=1 V. (1 point) In this part you are required to vary the minority carrier lifetime such that: (a) T = T₁ = 0.01μs (c) T₁ = T₁ =1μs Comment on the results obtained. Under what condition the recombination mechanism in the depletion region becomes significant? Explain with mathematical and physical reasoning. (1 point) For applied anode voltage V₁-0.9 V and T₁ = = 1μs, estimate the magnitude of the series resistance. What happens to the series resistance if No=10¹4 cm³ ? The forward biased I-V characteristics of real p-n diodes are affected by generation-recombination mechanisms in the depletion region, by the high injection and the series resistance of the diode. The I-V characteristics of a prototypical diode are plotted on a semi-logarithmic scale and four different regions can be distinguished as indicated on the figure below. 1.E+03 Current Density (A/cm²) 1E+01 1E-01 1E-03 1.E-05 1.E-07 1E-09 Depletion region recombinanon 0 Ideal chode (b) T₁=T=0.1μs P 0.3 High Injection 0.6 1 = 1, exp P() 77=2 Senes Resistance 0.9 Voltage (V) From the results presented in this figure it is evident that there is the ideal diode region where the current increases by one order of magnitude as the voltage is increased by 60 mV. This region is referred to as having an ideality factor, n, of one. The ideality factor is obtained by fitting a section of the curve to the following expression for the current: 1.2 Looking at the slope of the curve, to the left of the ideal diode region there is the region where the current is dominated by the trap-assisted recombination in the depletion region. This part of the curve has an ideality factor of two. To the right of the ideal diode region, the current becomes limited by high injection effects and by the series resistance. The above behavior can be simulated using PN Junction Lab at www.nanohub.org that is part of the ABACUS tool-based curricula https://nanohub.org/resources/abacus. You can directly access the pn- junction lab tool using the following link: https://nanohub.org/tools/pntoy. Hence, the purpose of this exercise is to examine how pronounced are each of the four regions for a diode with NA-10¹6 cm ³ and No=10¹5 cm ³. Sweep the anode voltage from VA=0V to V₁=1 V. (1 point) In this part you are required to vary the minority carrier lifetime such that: (a) T = T₁ = 0.01μs (c) T₁ = T₁ =1μs Comment on the results obtained. Under what condition the recombination mechanism in the depletion region becomes significant? Explain with mathematical and physical reasoning. (1 point) For applied anode voltage V₁-0.9 V and T₁ = = 1μs, estimate the magnitude of the series resistance. What happens to the series resistance if No=10¹4 cm³ ?