Role of AlN encapsulation of GaN during implant activation annealing

摘要

With the demonstration of implant doping of GaN and the resulting need to perform the activation anneal at 1100 C, details of thermal stability of the GaN surface needs to be understood. This work reports on the use of a sputtered AlN encapsulant to preserve the surface of GaN during such annealing. The surface was characterized by formation of Pt/Au Schottky contacts and by AES. Schottky contacts deposited an GaN annealed wtih the AlN encapsulant displayed good rectification properties while those formed on GaN annealed uncapped approached ohmic behavior. AES analysis supports the hypothesis that the uncapped sample has lost N from the very near surface which creates N-vacancies that act as donors and thereby form an n(sup +)-surface layer.