High performance solar-blind UV detector with Mg 0.472 Zn 0.528 O/Mg0.447Zn0.553O double layer structure on MgO substrate.

Mg0.472 Zn0.528 O/Mg0.447 Zn0.553 O double layer structure UV detectors are made on single structure MgO substrate by PLD method, and the effect of different thickness top MgZnO layer on the UV response characteristics of the detector are studied. Compared with the single layer MgZnO detector that made by Mg0.3 Zn0.7 O target, the Mg0.472 Zn0.528 O/Mg0.447 Zn0.553 O double layer detector with 30nm top layer, shows much higher deep UV response (21.3A/W at 265nm), much smaller dark current(66.9pA) and much higher signal-to-noise ratio(2.8×105 ) at 25V bias voltage. And the device also shows relative high response (23.1A/W) at 235nm deep UV light at 25V bias voltage, which is mainly attributed by the bottom MgZnO layer with higher Mg composition. When the top layer is 66.7nm thick, the response of the Mg0.472 Zn0.528 O/Mg0.447 Zn0.553 O detector reached 228.8A/W at 255nm under 25V bias voltage, the signal-to-noise ratio of which is 10573 under 20V bias voltage, and the near UV response of the device is also big because of more h-MgZnO in top MgZnO layer. When the top layer reached 90.2nm, there are much more h-MgZnO in the top MgZnO layer, the peak response of the Mg0.472 Zn0.528 O/Mg0.447 Zn0.553 O detector is just 6.65A/W at 320nm under 25V bias voltage, the signal-to-noise ratio of which is 1248. The high Mg composition bottom MgZnO decrease the dark current of the Mg0.472 Zn0.528 O/Mg0.447 Zn0.553 O detector, both the 2DEG effect of the double layer structure and the amplify effect of the mix-phase MgZnO top layer, increased the Iuv and deep UV response of the Mg0.472 Zn0.528 O/Mg0.447 Zn0.553 O detector. Therefore, the double layer Mg0.472 Zn0.528 O/Mg0.447 Zn0.553 O detector is more sensitive at faint deep UV light compared with previous reported MgZnO detectors, and the MgxZn1-xO/MgyZn1-yO detector shows similar Iuv and signal-noise-ratio at faint deep UV light as high-temperature fabricated AlxGa1-xN/AlyGa1-yN detectors.&#xD.