Breakdown Electric Field of GaN p<sup>+</sup>-n and p-n<sup>+</sup>Junction Diodes With Various Doping Concentrations
Takuya Maeda, Tetsuo Narita, Shinji Yamada, Tetsu Kachi, Tsunenobu Kimoto, Masahiro Horita, Jun Suda
Abstract
Breakdown characteristics in homoepitaxial GaN p-n junction diodes with p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -n and p-n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> junctions with relatively heavy doping concentrations are systematically investigated. The devices have vertical deep mesa etch termination, which enables uniform (nearly ideal) avalanche breakdown without electric field (E-field) crowding at the device edge. For p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -n junction, breakdown E-field of 3.0, 3.3 and 3.8 MV/cm and breakdown voltage (BV) of 340, 207 and 128 V were achieved at the donor concentrations of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${7.5}\times {10}^{{16}}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${1.5}\times {10}^{{17}}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${3.1}\times {10}^{{17}}$ </tex-math></inline-formula> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> , respectively. For p-n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> junction, breakdown E-field of 3.2, 3.3 and 4.0 MV/cm and BV of 235, 180 and 110 V were achieved at the acceptor concentrations of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${1.3}\times {10}^{{17}}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${1.8}\times {10}^{{17}}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${4.1}\times {10}^{{17}}$ </tex-math></inline-formula> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> , respectively. No significant difference of the breakdown characteristics between n-type and p-type voltage-blocking layers was observed. These results are consistent with numerical simulations using impact ionization coefficients (IICs) in GaN reported in our previous studies.