Breakdown Electric Field of GaN p+-n and p-n+ Junction Diodes With Various Doping Concentrations

Breakdown characteristics in homoepitaxial GaN p-n junction diodes with p
⁺
-n and p-n
⁺
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
⁺
-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
${7.5}\times {10}^{{16}}$
,
${1.5}\times {10}^{{17}}$
,
${3.1}\times {10}^{{17}}$
cm
⁻³
, respectively. For p-n
⁺
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
${1.3}\times {10}^{{17}}$
,
${1.8}\times {10}^{{17}}$
,
${4.1}\times {10}^{{17}}$
cm
⁻³
, 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.