Temperature Dependent Photoluminescence Studies of Mn Doped ITO Thin Films

Transparent conducting oxides (TCOs) have attracted a lot of attention in recent years due to their vast applications in flat panel displays, LEDs, solar cells, and wearable electronics. TCOs are electrically conductive, and their large energy band gap makes them optically transparent. Such versatile materials could potentially be used in spintronic devices if some degree of ferromagnetism can be achieved. In this study we optically investigate the effects of manganese doping on the energy band structure of Indium Tin Oxide (ITO), a widely used TCO. Thin films of ITO doped with various Mn concentrations are deposited on quartz substrates by DC magnetron sputtering. We then use low temperature photoluminescence (PL), transmission measurements, ellipsometry, and x-ray diffraction to characterize these films. The PL measurements reveal blue and UVA emission peaks. The blue emission is also consistent with blue absorption bands from our ellipsometry measurements, and it is tentatively attributed to the indirect bandgap of ITO. The PL intensity decreases with increasing Mn concentration which is attributed to upward shift of the valence band. Temperature dependent PL measurements show a decrease in the PL intensity and a red shift of the blue peak with increasing temperature. To our knowledge, these are the first temperature dependent optical studies of Mn doped ITO samples.



The support of the 4-VA at JMU is gratefully acknowledged.