Light polarization sensitive photodetectors with m- and r-plane homoepitaxial ZnO/ZnMgO quantum wells

Homoepitaxial ZnO/(Zn, Mg) O multiple quantum wells (MQWs) grown with m-and r-plane orientations are used to demonstrate Schottky photodiodes sensitive to the polarization state of light. In both orientations, the spectral photoresponse of the MQW photodiodes shows a sharp excitonic absorption edge at 3.48 eV with a very low Urbach tail, allowing the observation of the absorption from the A, B and C excitonic transitions. The absorption edge energy is shifted by similar to 30 and similar to 15 meV for the m-and r-plane MQW photodiodes, respectively, in full agreement with the calculated polarization of the A, B, and C excitonic transitions. The best figures of merit are obtained for the m-plane photodiodes, which present a quantum efficiency of similar to 11%, and a specific detectivity D* of similar to 6.4 x 10(10) cm Hz(1/2) /W. In these photodiodes, the absorption polarization sensitivity contrast between the two orthogonal in-plane axes yields a maximum value of (R-perpendicular to/R-parallel to)(max) similar to 9.9 with a narrow bandwidth of similar to 33 meV. (C) 2015 AIP Publishing LLC.