1. Faculty of Engineering; Universiti Teknologi Brunei; Jalan Tungku Link Gadong BE1410 Brunei Darussalam
2. Institute of Materials Research and Engineering; Agency for Science, Technology and Research; 3 Research link Singapore 117602 Singapore
3. Faculté de saint Jérôme; Institut Matériaux Microélectronique Nanosciences de Provence (IM2NP); CNRS UMR 7334, Case 151 13397 Marseille Cedex 20 France