Epilayer Thickness and Doping Density Variation Effects on Current-Voltage (I-V) Characteristics of n-GaN Schottky Diode

The epilayer thickness and doping density variation effects on the (I-V) characteristics of n-GaN schottky diode are determined numerically. In this work the epilayer thickness of n-GaN schottky diode are varied from 3μm ~11μm while doping density are varied from 1×10 12 cm -3 ~ 1×10 17 cm -3 . The simulation work is conducted using Atlas/Blaze developed by Silvaco. The various models such as Srh (Shockley-Read Hall), Cvt (Lombardi model), Auger, Impact (Grants model), Bgn (Band gap narrowing), Conmob (concentration dependent mobility) is used to get optimum (I-V) characteristics of n-GaN schottky diode. We find that in forward biased as the epilayer thickness varied from 3μm ~11μm at constant doping density 1×10 12 cm -3 the forward current decreases due to the increase in series resistance, on the other hand the forward current increased by lowering the epilayer thickness up to 3μm and increasing the doping density ~ 1×10 17 cm -3 . In reverse biased the selection of doping density and epilayer thickness directly determined the target reverse breakdown voltage of the device. As the epilayer thickness varied from 3μm ~11μm at constant doping density 1×10 12 cm -3 , the breakdown voltage increased due to increased in the depletion width, while the breakdown voltage reduced as doping density varied from 1×10 12 cm -3 ~ 1×10 17 cm -3 at constant epilayer thickness of 3μm. Hence we conclude that forward current and breakdown voltage have strong, inverse relation between epilayer thickness and doping density.