Growth of p-type Cu-doped GaN films with magnetron sputtering at and below 400 1C Kidus Yohannes, Dong-Hau Kuo n Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan article info Keywords: GaN Copper doping abstract p-Type Cu-doped GaN (Cu–GaN) films have been grown with a cermet target by magnetron sputtering at 100–400 1C on AlN-coated Si substrates. The effects of growth temperature on microstructure, composition, and electrical properties of the Cu–GaN have been systematically investigated. The results indicated that growth kinetics had affected the film performance. Electrical properties of Cu–GaN changed with the change in Cu ratio. The Cu Ga 1À acceptor can be the reason for the p-type behavior. The average surface roughness of Cu–GaN films was 2.65 70.41 nm. Its growth rate and electrical conductivity were 2.30 70.26 μmh À1 and 0.05–0.79 S cm À1 , respectively. & 2014 Elsevier Ltd. All rights reserved. 1. Introduction III-Nitride semiconductors with their wide band gap have become very important materials for optoelectronic applications. Gallium nitride (GaN) is one of the most promising wide-band-gap semiconductors for the devel- opment of high efficiency UV–vis photonic devices due to its direct band gap [1,2]. It is also an important semicon- ductor widely used for optoelectronic and power applica- tions such as blue light emitting diodes (LEDs), blue laser diodes, heterojunction bipolar transistors, and high tem- perature electronic devices. In order to produce these devices, both n- and p-type doping of GaN are needed [3–5]. Electrical properties of III-nitrides can be modified by composition adjustment. p-type conductivity in GaN with magnesium doping can be a milestone for the develop- ment of white light LED [2,6]. During the MOCVD growth, it has found that the incorporation of Mg in GaN is facilitated by simultaneously co-doping with hydrogen, which can be subsequently removed from the sample by post-growth annealing [2,7]. Magnesium (Mg) doping in p- type GaN is considered to have its low incorporation fraction and ionization ratio [8]. A precise and repeatable control in p-type conductivity of GaN-based semiconductors has become increasingly critical [9]. Most of the research groups working on GaN-based materials have focused on the growth techniques of metalorganic chemical vapor deposi- tion (MOCVD) and molecular beam epitaxy (MBE). MOCVD has been widely used in the commercialization of GaN-based devices. Except for Mg, other impurities have also been investi- gated for the purpose of finding an acceptor of GaN with smaller ionization energy, which could contribute to enhance p-type conductivity. One possibility is the group II element beryllium (Be). Be is a common p-type dopant in the more conventional III–V compound semiconductors such as GaN and has a low activation energy of about 60 meV, making it a promising candidate for p-type doping in GaN [10]. However, Be has the potential of being incorporated as an interstitial impurity because of its small size and expected to be a double donor, which will compensate the Be Ga acceptor. Zn Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/mssp Materials Science in Semiconductor Processing http://dx.doi.org/10.1016/j.mssp.2014.05.010 1369-8001/& 2014 Elsevier Ltd. All rights reserved. n Corresponding author. E-mail address: dhkuo@mail.ntust.edu.tw (D.-H. Kuo). Materials Science in Semiconductor Processing ] (]]]]) ]]]–]]] Please cite this article as: K. Yohannes, D.-H. Kuo, Materials Science in Semiconductor Processing (2014), http://dx.doi. org/10.1016/j.mssp.2014.05.010i