Wide range variation of resonance wavelength of GaZnO plasmonic metamaterials grown by molecular beam epitaxy with slight modification of Zn effusion cell temperatures

Abstract The innovative growth condition of heavily Ga-doped ZnO (GaZnO) plasmonic metamaterials is reported in this article. GaZnO epilayers are deposited by molecular beam epitaxy (MBE) with small variation of Zn effusion cell temperatures. The variation of Zn effusion cells temperatures are 330, 335, and 340 oC corresponding to Ga doping concentration 6.8, 6.3, and 3.2 at.%, respectively, which are obtained from the measurements of energy-dispersive X-ray spectroscopy (EDX). Temperatures of Ga effusion cell and sapphire substrate are fixed at 735 and 250 oC in the growth. Hall effect measurements exhibiting free electron concentration of all samples approach 1021 cm-3. The lowest strain/stress (0.08%/0.34 GPa), the largest crystalline size (47.5 nm) , the highest Hall mobility (30.1 cm2/Vs) , and the lowest material loss of GaZnO epilayers are observed in Ga doping concentration 6.3 at.% sample. Statistical analysis of root mean square (RMS) surface roughness declines from 3.1 to 1.74 nm in the atomic force microscope (AFM) measurements when the doping is increased from 3.2 to 6.8 at.%. Wide range variation of plasmonic resonance wavelength from 1333 to 1515 nm with the raise of Ga doping concentration is acquired through the analysis of spectroscopic ellipsometry measurements. Slight variations of Zn effusion cell temperatures in the range of 330~340 oC bring about efficient and drastic change of Ga doping concentration as well as wide range variation of plasmonic resonance wavelength (1333~1515 nm) for the applications in fiber-optic communication.