Designing a 2kV GaN p-i-n Diode Considering the Photon Recycling Phenomenon

Wide bandgap semiconductors, such as Gallium Nitride (GaN), are transforming high-power device applications due to their superior critical electric field strength and exceptional thermal conductivity compared to silicon. In bipolar devices, conductivity modulation is essential for achieving enhanced performance; however, GaN's inherently short carrier lifetime, predominantly caused by radiative recombination, presents a significant challenge for bipolar devices. Photon recycling, a phenomenon where photons emitted through radiative recombination are reabsorbed, generating additional carriers, offers a promising approach to improve conductivity modulation in GaN-based devices. This study explores the feasibility of leveraging photon recycling to enhance conductivity modulation in vertical GaN p-i-n diodes, employing SIL VACO TCAD simulations to assess its impact. Both intrinsic photon recycling (IPR) and extrinsic photon recycling (EPR) mechanisms are evaluated for their influence on the effective carrier lifetime and specific on-resistance <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{R}_{\text{ON},\text{SP}})$</tex>. Two device architectures are investigated: a baseline structure designed for standard performance and an optimized design targeting a 2000V breakdown voltage. Simulation results reveal that photon recycling significantly bolsters conductivity modulation, particularly through EPR, which demonstrates the most substantial reduction in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{R}_{\text{ON},\text{SP}})$</tex> under low forward voltage conditions. A factor of 1.03 improvements in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{R}_{\text{ON}, \text{SP}}$</tex> is demonstrated for the 2 kV device whereas the improvement factor for the device with 9 μm drift layer is in the range of 1.4 − 2.2. These findings underscore the potential of photon recycling as a novel strategy to overcome GaN's intrinsic material limitations for the medium voltage power devices.