Optical and morphological properties of MBE grown wurtzite CdxZn1−xO thin films

Abstract Wurtzite Cd x Zn 1− x O epilayers with cadmium concentrations ranging from x  = 0.02 to 0.30 were investigated using photoluminescence, transmission/reflection spectroscopy, and atomic force microscopy. The Cd x Zn 1− x O photoluminescence peak was found to shift through the visible region from 421 (2.95 eV) to 619 nm (2.0 eV) as the cadmium concentration was increased from 2% to 30%. An additional broad photoluminescence peak was observed and is attributed to deep levels – the center of the broad peak was found to shift from 675 to 750 nm as the cadmium concentration was increased. RMS roughness of the epilayers increased from 1.5 nm ( x  = 0.02) to 9.2 nm ( x  = 0.30), as determined from atomic force microscopy. The demonstrated visible wavelength tunability throughout the visible range verifies the viability of using wurtzite Cd x Zn 1− x O compounds for visible light emission in future optoelectronic devices.