Characterization of p- and n-type GaN thin films grown by plasma-assisted molecular beam epitaxy

III-Nitrides semiconductor compound has been well recognized and become potential material for optoelectronics device applications as it has superior properties such as large and direct band gap, high-saturation velocity and high breakdown field [1]. High quality III-Nitrides materials have been grown by various methods and molecular beam technique (MBE) has become one of the leading growth techniques for nitrides as it offers possibility of in-situ monitoring of the growth process. This is demonstrated by the possible of various optoelectronic devices such as LED, photodetector and solar cells [2, 3]. Nevertheless, there are still issues in the growth process of nitrides material, particularly in producing highly conductive p-type doping in GaN. This is due to deep acceptor level of Mg atoms and also the solubility limit of Mg in GaN [4] that leads to high resistivity and low mobility.