Wafer-Bonded p-n Heterojunction of GaAs and Chemomechanically Polished N-Polar GaN

Abstract

This letter reports wafer-bonded p-n heterojunction diodes, which consist of GaAs and chemomechanically polished N-polar GaN. The measured <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> show well-behaved p-n junction characteristics. The built-in voltage extrapolated from the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> is 0.2 V less than the theoretical, suggesting the existence of interface states. However, this offset is much less than that (1.14 V) reported of wafer-bonded GaAs/Ga-polar GaN p-n diodes. The limited maximum current suggests pinning of the Fermi level at interface traps near the conduction band accessed under forward bias. Yet, this junction shows promise as a collector junction for wafer-bonded devices to achieve higher breakdown voltages.